Green Synthesis of Fe₃O₄/Chitosan Nanoparticles Utilizing Moringa Oleifera Extracts and Their Surface Plasmon Resonance Properties

Abstract

In this study, a simple, rapid, and environmentally friendly green approach for synthesizing Fe 3 O 4 and Fe 3 O 4 /chitosan nanoparticles with various concentrations was developed. The nanoparticles had a spherical shape with a cubic inverse spinel structure. The functionalization of the Fe 3 O 4 nanoparticles using chitosan increased the crystallite size of the nanoparticles from 7.2 to 7.8 nm. The Fourier transform infrared spectra of the Fe 3 O 4 /chitosan nanoparticles showed the existence of the characteristic peaks of chitosan in addition to a peak at 578 cm −1 , which corresponds to the stretching of the Fe−O group. The UV-visible spectra demonstrated a wide absorption band with the appearance of small peaks of chitosan absorption at 205 and 215 nm. The saturation magnetization of the Fe 3 O 4 was 54.1 emu g −1 . The surface plasmon resonance (SPR) measurements showed an enhancement in the SPR angle as the ratio of chitosan to Fe 3 O 4 increased, wherein the angle shift from 0.17° to 1.91°. The chitosan covering the Fe 3 O 4 nanoparticle surface caused the refractive index to change, which increased the SPR angle shift. The obtained results indicated that the SPR properties of the Fe 3 O 4 nanoparticles were significantly improved by modification with chitosan. These results also indicated that the use of chitosan in Fe 3 O 4 nanoparticles can enhance SPR properties, which has potential for future SPR-based sensor applications.