Computational Study of Sensitivity Enhancement in Surface Plasmon Resonance (SPR) Biosensors by Using the Inclusion of the Core-Shell for Biomaterial Sample Detection

Abstract

A theoretical analysis and computational study of biomaterial sample detection with surface plasmon resonance (SPR) phenomenon spectroscopy are presented in this work with the objective of achieving more sensitive detection. In this paper, a Fe3O4@Au core-shell, a nanocomposite spherical nanoparticle consisting of a spherical Fe3O4 core covered by an Au shell, was used as an active material for biomaterial sample detection, such as for blood plasma, haemoglobin (Hb) cytoplasm and lecithin, with a wavelength of 632.8 nm. We present the detection amplification technique through an attenuated total reflection (ATR) spectrum in the Kretschmann configuration. The system consists of a four-layer material, i.e., prism/Ag/Fe3O4@Au + biomaterial sample/air. The effective permittivity determination of the core-shell nanoparticle (Fe3O4@Au) and the composite (Fe3O4@Au + biomaterial sample) was done by applying the effective medium theory approximation, and the calculation of the reflectivity was carried out by varying the size of the core-shell, volume fraction and biomaterial sample. In this model, the refractive index (RI) of the BK7 prism is 1.51; the RI of the Ag thin film is 0.13455 + 3.98651i with a thickness of 40 nm; and the RI of the composite is varied depending on the size of the nanoparticle core-shell and the RI of the biomaterial samples. Our results show that by varying the sizes of the core-shell, volume fraction and the RIs of the biomaterial samples, the dip in the reflectivity (ATR) spectrum is shifted to the larger angle of incident light, and the addition of a core-shell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity. For a core-shell with a radius a = 2.5 nm, the sensitivity increased by 10% for blood plasma detection, 47.72% for Hb cytoplasm detection and by 22.08% for lecithin detection compared to the sensitivity of the conventional SPR-based biosensor without core-shell addition.

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

“…This phenomenon occurs at a specific critical incident angle θ sp and a wavelength of light λ. The value of θ sp strongly depends on the refractive index of the sensing dielectric medium (Ekariyani, et al, 2016;Oktivina, et al, 2017;Widayanti, et al, 2018). In this case, the sensing dielectric medium involves the nanomaterials used in the SPR system.…”

“…Experimentally, (Ekariyani, et al, 2016;Oktivina, et al, 2017) had used Fe 3 O 4 nanoparticles as an active material for increasing the biosensor response. In 2018 (Widayanti, et al, 2018) had conducted a computational study on the use of the core-shell structure of Fe 3 O 4 -Au as an active material for enhancing the sensitivity of the sensor.…”

Magneto-optic surface plasmon resonance properties of core-shell Fe3O4@Ag nanoparticles

“…Furthermore, metal NPs have been used in the SPR biosensor to immobilise molecules, optimise the detection, and enhance the sensitivity [20][21][22][23][24][25]. We previously reported that the use of Fe 3 O 4 NPs in the conventional SPR system shows the small SPR angle shift [20].…”

“…Therefore, the use of Fe 3 O 4 NPs with applying an external magnetic field may be purposed to improve the SPR system. The addition of coreshell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity [21][22][23][24]. The core-shell NPs has the advantageous properties such as the increases of dispersibility and chemical stability [25].…”

Development and validation of immunoassay for whole cell detection of Brucella abortus and Brucella melitensis

“…Surface Plasmon Resonance (SPR) validates immobilization of IgG antibody, viable WC and DNA by detecting high molecular analytes whereby ligand binding (association) increases mass on the chip surface and on dissociation decreases the mass. Such changes produce direct detectable signal by affecting the refractive index, RI 30,31 . Escherichia coli detection by SPR was reported by immobilizing anti-Escherichia coli antibody having LOD at 10 4 CFU mL −1 with functionalized gold substrate (acid-thiol) and 10 3 CFU mL −1 with gold nanoparticles respectively 32 .…”