Tunable SERS effect of the silver rod and magnetite nanocomposite with different magnetic field and aspect ratios

摘要

Silver rod nanoparticles with three different aspect ratios were obtained adopting the seed mediated growth method, where the seed solution of the silver nanoparticles is 0.06, 0.15, and 0.2 mL, respectively. Utilizing the plasmon resonance of the silver rod nanoparticles, we fabricate the SERS substrate with the superparamagnetic nanoparticles, which renders the substrate with magnetic field controllability. By tuning the magnitude of the magnetic field from 1450, 1900, 2500 to 3500 gauss, Raman optical activity was carried out with the crystal violet (CV) as a probed molecule. The experimental results show that enhanced and repeatable Raman spectra can be obtained with increased magnetic field and the detection limit can reach 10~10 M, which was caused by the uniform array of the metallic nanoparticles. Moreover, the aspect ratio was another factor to tune the plasmon resonant properties of the silver rod nanoparticles. Thus, controllable SERS activity can be obtained based on our prepared composite SERS substrate, which renders it a feasible way to broaden its application in the single molecule detection and biomedicine diagnostic in a controlled way.