Optimizing and Quantifying Gold Nanospheres Based on LSPR Label-Free Biosensor for Dengue Diagnosis

Abstract

The localized surface plasmon resonance (LSPR) due to light–particle interaction and its dependence on the surrounding medium have been widely manipulated for sensing applications. The sensing efficiency is governed by the refractive index-based sensitivity (ηRIS) and the full width half maximum (FWHM) of the LSPR spectra. Thereby, a sensor with high precision must possess both requisites: an effective ηRIS and a narrow FWHM of plasmon spectrum. Moreover, complex nanostructures are used for molecular sensing applications due to their good ηRIS values but without considering the wide-band nature of the LSPR spectrum, which decreases the detection limit of the plasmonic sensor. In this article, a novel, facile and label-free solution-based LSPR immunosensor was elaborated based upon LSPR features such as extinction spectrum and localized field enhancement. We used a 3D full-wave field analysis to evaluate the optical properties and to optimize the appropriate size of spherical-shaped gold nanoparticles (Au NPs). We found a change in Au NPs’ radius from 5 nm to 50 nm, and an increase in spectral resonance peak depicted as a red-shift from 520 nm to 552 nm. Using this fact, important parameters that can be attributed to the LSPR sensor performance, namely the molecular sensitivity, FWHM, ηRIS, and figure of merit (FoM), were evaluated. Moreover, computational simulations were used to assess the optimized size (radius = 30 nm) of Au NPs with high FoM (2.3) and sharp FWHM (44 nm). On the evaluation of the platform as a label-free molecular sensor, Campbell’s model was performed, indicating an effective peak shift in the adsorption of the dielectric layer around the Au NP surface. For practical realization, we present an LSPR sensor platform for the identification of dengue NS1 antigens. The results present the system’s ability to identify dengue NS1 antigen concentrations with the limit of quantification measured to be 0.07 μg/mL (1.50 nM), evidence that the optimization approach used for the solution-based LSPR sensor provides a new paradigm for engineering immunosensor platforms.

Nanoplasmonic Avidity-Based Detection and Quantification of IgG Aggregates

“…It is also possible that some of the dimers blocked only one ligand site but orienting the dimer partly outside the LSPR sensing depth, therefore generating a similar response as a monomer. The sensing depth of the LSPR nanostructures used here is about 15–20 nm. , A single IgG molecule (∼12 nm) bound to a protein A ligand (∼2.5 nm) consequently occupies almost the entire sensing depth.…”

“…The sensing depth of the LSPR nanostructures used here is about 15–20 nm. 41 , 42 A single IgG molecule (∼12 nm) bound to a protein A ligand (∼2.5 nm) consequently occupies almost the entire sensing depth.…”

Tailoring the Scattering Response of Optical Nanocircuits Using Modular Assembly

“…The for convex shapes NPs such as for spheres, rods, cubes etc., is obtained as = where S represents the surface area and V is the volume. The dielectric function is frequency dependent on the spontaneous polarization and the dielectric constant decreases as the NP size increases [ 26 ], which is depicted in Figure 3 . It can be seen that reducing the may tailor for both real and imaginary parts of gold dielectric function.…”

Impact of nanotechnology on conventional and artificial intelligence-based biosensing strategies for the detection of viruses

“…B Optical based nanobiosensor: (i) Schematic of the principle of LSPR, (ii) The radius of the nanoparticle is plotted against the LSPR peak resonance wavelength (black spheres) and full width half maximum (blue cubes). Adapted from Farooq et al [ 172 ] under Creative commons Attribution 4.0. (iii) Principle of Surface enhanced Raman scattring (iv) Raman spectra of rhodamine 6 G molecule collected on various film substrates such as Au/AgNP/crossed CNT film (#1), AgNP/crossed CNT film (#2), AuNP/crossed CNT film (#3) Adapted from Wei et al [ 173 ] under Creative commons Attribution 4.0.…”

“… Adapted from Farooq et al [ 172 ] under Creative commons Attribution 4.0. (iii) Principle of Surface enhanced Raman scattring (iv) Raman spectra of rhodamine 6 G molecule collected on various film substrates such as Au/AgNP/crossed CNT film (#1), AgNP/crossed CNT film (#2), AuNP/crossed CNT film (#3) Adapted from Wei et al [ 173 ] under Creative commons Attribution 4.0.…”