Enhancing the Chemically-Induced Optical Properties Supported by the Localized Surface Plasmon Resonance in Anisotropic Single Gold Bipyramids.

Abstract

The localized surface plasmon resonance (LSPR)-based biosensors and others optical devices that employ gold nanoparticles (AuNPs) have shown tremendous advantages over techniques such as fluorescence and chemiluminescence in recent developments of nanoscience and nanotechnology. In one hand,the localized surface plasmon resonance (LSPR) biosensors are ultra-high refractive index sensing, they have a fast sensor response, they enable real-time detection and can be use in a label-free technique. In the other hand, instead surface plasmon resonance (SPR) in a bulk gold, gold nanoparticles (AuNPs) exploited under the quasi-static boundary condition offer an unprecedented platform for investigating on desired optical and spectroscopic properties at nanoscale. Relative to other metallic nanoparticles supporting LSPR signal, AuNPs have drawn the greatest attention and interest owing to their biocompatibility with high chemical and physical stability. More importantly, AuNPs easy functionalization with organic and biological molecules fostered their use as LSPR-based sensors materials. However, LSPR still has many fundamental limitations that cause LSPR based sensors efficiency to be low compared to surface plasmon polariton (SPP) sensors. One major limitation of LSPR sensor effectiveness is changes in the magnitude of the shift across the spectrum due to the shape of the LSPR peak when monitoring changes of the nanoparticle local environment at their surface. This results in unsymmetrical broadening and was found to have a negative impact on sensing efficiency. Therefore, for optimal and efficient engineering of gold nanoparticles (AuNPs) LSPR-based sensors and others optical devices, AuNPs LSPR based unique optical properties must be fully understood and harnessed. As a first report, we devoted a particular focus on LSPR scattering inflection points (IFs) of single gold bipyramids (AuBPs). The findings reveal that tracking LSPR IFs exhibit high sensitivity over their counterpart LSPR peak shift locations. More importantly, the limitation on unsymmetrical broadening is no more a limitation on the changes of the magnitude of the shift across the spectrum due to the shape of the LSPR peak.