Theoretical Investigation of Size, Shape and Aspect Ratio Effect on the LSPR Sensitivity of Hollow-Gold Nanoshells

TL;DR

This study theoretically investigates how shape, size, and aspect ratio influence the localized surface plasmon resonance (LSPR) sensitivity of hollow gold nanoshells, revealing optimal geometries for biosensing applications.

Contribution

It provides a comprehensive theoretical analysis of how shape, size, and aspect ratio affect LSPR sensitivity in hollow gold nanoshells, identifying geometries with maximum sensitivity.

Findings

Rectangular block and rod-shaped nanoshells show highest sensitivity.

Higher aspect ratios increase LSPR sensitivity.

Thinner shells enhance sensitivity.

Abstract

The change in refractive index around plasmonic nanoparticles upon binding to biomolecules is routinely used in localized surface plasmon resonance (LSPR) based biosensors and in bio-sensing platforms. In this study, the plasmon sensitivity of hollow gold (Au) nanoshells is studied using theoretical modeling where the influence of shape, size, shell thickness and aspect ratio are addressed. Different shapes of hollow Au nanoshells are studied that include: sphere, disk, triangular prism, rod, ellipsoid, and rectangular block. Multi-layered Mie theory and discrete dipole approximation (DDA) were used to determine the LSPR peak position, and LSPR sensitivity as a function of size, shell thickness, shape, and aspect ratio. The change in LSPR peak wavelength per unit refractive index is defined as the sensitivity, and interesting results were obtained from the analysis. The rectangular block and rod-shaped Au nanoshells have shown maximum LSPR sensitivity when compared to other shaped Au nanoshells. In addition, increased sensitivity was observed for higher aspect ratio as well as for smaller shell thicknesses. The results are rationalized based on the inner and outer surface plasmonic coupling.