Optical Properties of Fe₃O₄/Chitosan and Its Applications for Signal Amplifier in Surface Plasmon Resonance Sensor

Abstract

The Fe3O4/chitosan nanocomposite is one of the attractive functional materials. It can be applied as active material in a sensor system for an instant Surface Plasmon Resonance (SPR) based sensor. This research aimed at investigating the optical properties of Fe3O4/chitosan and its effect on the SPR angle. The synthesis of nanoparticles used the coprecipitation method. Encapsulation was carried out at a temperature of 50 o C for about 60 minutes. The samples were characterized for their structural properties and phase composition by using X-ray diffraction (XRD) techniques. Their optical properties were characterized by using the Specular Reflectance UV-Vis Spectroscopy technique. The optical properties, such as absorbance (A), absorption coefficient (α), refractive index (n), extinction coefficient (k), optical gap energy (Eg), and Urbach energy (Eu) are investigated. The measurement of the SPR angle toward the ATR curve was carried out in a range of 30 o -60 o by using the Kretschmann configuration. The results show that encapsulation affects the optical properties of the nanoparticles. The SPR angle of prism/Au/Fe3O4/Air and prism/Au/Fe3O4-Chitosan/Air system is about 50.04 o and 50.93 o , consecutively. Chitosan affects an increase of the SPR signal toward the reflectivity where the SPR angle exists. These results imply a future prospective application of the Fe3O4/Chitosan as a signal amplifier material for the SPR sensor.

Green Synthesis of Magnetic Supramolecules β-Cyclodextrin/Iron Oxide Nanoparticles for Photocatalytic and Antibacterial Applications

“…Prior studies have yielded comparable outcomes . In addition, it is possible to attribute the alteration in the hue of the initial solution from a yellow shade to a darker one as the synthesis process progresses to the surface plasmon resonance excitation phenomenon …”

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

“…The SPR spectra output (reflected light versus the angle of the incident light) was displayed by a computer, and then analyzed by observers. 32,57,60,61 SPR spectra result from plasmon excitation by an evanescent wave incident at a particular angle was greater than the critical angle. An evanescent wave is formed when a propagating laser beam in the prism encounters the metal-dielectric interface.…”

“…22,23 Therefore, Fe 3 O 4 /CS nanoparticles have been widely used in various fields, such as heavy metal adsorption, [24][25][26][27] metal determination, 28 enzyme immobilization, 29 targeted drug delivery, 30 magnetic hyperthermia, 31 and surface plasmon resonance (SPR). 32 In the case of SPR, the CS-modified Fe 3 O 4 nanoparticles present several advantages, such as exhibiting good stability that contributes to plasmon-plasmon coupling, amplifying SPR signals to enhance sensitivity, offering active sites of functional groups to facilitate nanoparticle-molecule interactions, and acting as biocompatible and biodegradable active materials in SPR applications. 32 Different approaches have been employed for the efficient synthesis of iron oxide nanoparticles of different shapes and sizes.…”

“…32 In the case of SPR, the CS-modified Fe 3 O 4 nanoparticles present several advantages, such as exhibiting good stability that contributes to plasmon-plasmon coupling, amplifying SPR signals to enhance sensitivity, offering active sites of functional groups to facilitate nanoparticle-molecule interactions, and acting as biocompatible and biodegradable active materials in SPR applications. 32 Different approaches have been employed for the efficient synthesis of iron oxide nanoparticles of different shapes and sizes. 33 A study reported that among the methods used to synthesize iron oxide nanoparticles, 90% are chemical processes, followed by physical methods (8%) and biological methods (2%).…”

“…49 Previously, we successfully synthesized Fe 3 O 4 nanoparticles, Fe 3 O 4 /CS, and CS-polyethylene glycol (PEG) nanoparticles using chemical synthesis and used them as active materials in SPR. 32,50,51 In the literature, Fe 3 O 4 /CS nanoparticles synthesized using MO for use in SPR studies have never been reported. A recent study revealed that the green synthesis of noble metal nanoparticles (Ag) using MO shows the capability of amplifying the SPR signal; 52 thus, synthesizing Fe 3 O 4 /CS using MO for application in SPR-based sensors is advantageous.…”