| Abstrak/Abstract |
The application of a magnetic field to surface plasmon resonance (SPR) is very attractive for biosensing applications because it can increase the performance and detection accuracy of the SPR biosensors. Ferrite nanoparticles (NPs) have been used for surface modification to accommodate the magneto-optical effect. This study successfully investigated and compared the characteristics of the effect of the magnetic field with a transverse configuration on SPR on Fe3O4, CoFe2O4, and MnFe2O4 NPs prepared using the green synthesis method with Moringa oleifera extract, which is environmentally friendly, cost-effective, and sustainable. The effect of the magnetic field on the SPR sensor was investigated using a Kretschmann configuration with a prism/Au thin film/ferrite NP/air layer structure with a wavelength of 632.8 nm. Magnetic fields of 40, 50, and 60 Oe were applied to the surface of the layered structure, and the SPR angle shift was directly proportional to the magnitude of the magnetic field. The angle shift of SPR with magnetic fields of 40, 50, and 60 Oe was greater than that on the SPR sensor without the magnetic field applied. The angle shift for Fe3O4 NPs was +0.55°, +0.62°, and +0.67°; that for CoFe2O4 NPs was +0.42°, +0.46°, and +0.49°, and for MnFe2O4 NPs it was +0.25°, +0.29°, and +0.31°, respectively. The SPR angles of the Fe3O4 NPs were +0.50°, CoFe2O4 NPs is +0.36°, and MnFe2O4 NPs is +0.19°, respectively. Meanwhile, the value of full width half maximum (FWHM) increases after application of the magnetic field; the FWHM of Fe3O4, CoFe2O4, and MnFe2O4 NPs with 60 Oe is 2.29, 2.28, and 2.29, respectively. In addition, the detection accuracies (DA) of the sensors with Fe3O4, CoFe2O4, and MnFe2O4 NPs with 60 Oe were 0.29, 0.21, and 0.13, respectively. Increases in the SPR angle, FWHM, and DA indicated an increase in the performance of the SPR biosensor. A non-reciprocal investigation showed that the SPR characteristics changed when a magnetic field was applied in different directions. These results indicate that the effect of the magnetic field on SPR systems using ferrite NPs can improve the performance of SPR-based biosensors. |
