磁性Ag@Fe3O4@C负载纳米金的制备及其SERS性能

利用一步溶剂热法制备了具有核壳结构的Ag@Fe_3O_4磁性纳米颗粒,然后以葡萄糖作为碳源对Ag@Fe_3O_4进行包覆,再利用酰胺化反应成功的将聚乙烯亚胺(PEI)修饰到Ag@Fe_3O_4@C表面,最后以N-Au共价键的方式将Au纳米粒子组装到Ag@Fe_3O_4@C表面。以4-巯基苯甲酸(4MBA)为拉曼活性探针分子来考察该复合纳米材料的表面增强拉曼(SERS)性能。通过控制Au纳米粒子的加入量,来调节Ag@Fe_3O_4@C-Au复合纳米材料的SERS活性。通过实验测试及利用时域有限差分法(FDTD)得出不同纳米金用量包覆的Ag@Fe_3O_4@C磁性纳米颗粒对4MBA的SERS效果依次为Ag@Fe_3O_4@C-Au-40Ag@Fe_3O_4@C-Au-10Ag@Fe_3O_4@C-Au-60Ag@Fe_3O_4@C,其中Ag@Fe_3O_4@C-Au-40的饱和磁化强度为411 A·g-1,其对4MBA的检测限为1×10-9 mol·L-1。这种功能性复合材料既具有良好的SERS活性,又可通过外加磁场的方式实现对待测分子的分离、富集。

Preparation and SERS Performance of Magnetic Ag@Fe3O4@C Supported Gold Nanoparticles

An Ag@Fe₃O₄@C-Au microspheres has been developed which including the synthesis of Ag@Fe₃O₄ by one-step via a versatile solvothermal reaction, an interlayer of carbon shell coating around the Ag@Fe₃O₄ with glucose as carbon source, the surfuce of Ag@Fe₃O₄@C modified by PEI via amidation reaction, and the coating Au nanoparticles on the surface of Ag@Fe₃O₄@C. The enhancement effect in the Raman active was investigated by using 4-mercaptobenzoic acid (4MBA) molecules as a probe molecule. In addition, we have regulated the SERS behavior of Ag@Fe₃O₄@C-Au core-shell microspheres by adjusting the additional amount of Au nanoparticles (NPs). The magnetic hysteresis loops showed the saturation magnetization (Ms) values of Ag@Fe₃O₄@C-Au-40 are about 411 A·g^-1, and the SERS effect of 4MBA on different microspheres is Ag@Fe₃O₄@C-Au-40 > Ag@Fe₃O₄@C-Au-10 > Ag@Fe₃O₄@C-Au-60 > Ag@Fe₃O₄@C nanospheres, which was identified by Finite Difference Time Domain (FDTD). Furthermore, the low concentrations of 4MBA (1×10^-9 mol·L^-1) in the solution can be detected by the Ag@Fe₃O₄@C-Au-40 microspheres. In addition, the Ag@Fe₃O₄@C-Au microspheres can be recycled with magnet.