SYNTHESIS, CHARACTERIZATION, AND APPLICATION OF Fe3O4 NANOPARTICLES AS A SIGNAL AMPLIFIER ELEMENT IN SURFACE PLASMON RESONANCE BIOSENSING

Abstract

The Fe₃O₄ nanoparticle has potential applications to be active materials for biosensor. This research was aimed at synthesizing and applying Fe₃O₄ nanoparticles for signal amplification of Surface Plasmon Resonance (SPR)-based biosensor. The synthesis was carried out by using the coprecipitation method at a temperature of 80^oC for 60 minutes. NaOH of 5 molars was used as a precipitating agent. The Fe₃O₄ nanoparticles were characterized for their microstructure by using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. The crystallinity of nanoparticles is 87% and the crystallite size is 15.70 nm. The shape of Fe₃O₄ is nearly spherical. The optical properties were characterized by using Fourier Transform Infrared Spectroscopy (FTIR) and Specular Reflection UV-Vis Spectroscopy (SR UV-Vis). There were vibrations of Fe³⁺-O and Fe²⁺-O bonds at characteristic frequencies of 586.86 cm^-1 and 422.64 cm^-1. The direct and indirect optical gap energies were 3.43 eV and 3.10 eV. The magnetic properties measured by Vibrating Sample Magnetometer (VSM) confirmed that Fe₃O₄ was ferrimagnetic. The Fe₃O₄ was successful to be applied as a signal amplifier for SPR-based biosensors due to their optical and magnetic properties. The SPR angle shifted to a higher value and the change was 3.57^o.