Shape Effect on the Refractive Index Sensitivity at Localized Surface Plasmon Resonance Inflection Points of Single Gold Nanocubes with Vertices

Hui Bin Jeon,Philippe Vuka Tsalu,Ji Won Ha

doi:10.1038/s41598-019-50032-3

Hui Bin Jeon, Philippe Vuka Tsalu + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-50032-3

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Journal: Scientific Reports	Publication Date: Sep 20, 2019
Citations: 118	License type: open-access

Affiliation: University of Ulsan

Abstract

Plasmonic gold nanoparticles with sharp tips and vertices, such as gold bipyramids (AuBPs) and gold nanocubes (AuNCs), have been widely used for high-sensitivity localized surface plasmon resonance (LSPR) sensing. However, conventional LSPR sensors based on frequency shifts have a major disadvantage: the asymmetry and broadening of LSPR peaks because of instrumental, environmental, and chemical noises that limit the precise determination of shift positions. Herein, we demonstrated an alternative method to improve the efficiency of the sensors by focusing on homogeneous LSPR scattering inflection points (IFs) of single gold nanoparticles with a single resonant mode. In addition, we investigated the effect of the shape and vertices of AuNCs on the refractive index (RI) sensitivity of homogeneous LSPR IFs by comparing with gold nanospheres (AuNSs) of similar size. The results show that for both AuNCs and AuNSs, tracking homogeneous LSPR IFs allows for higher RI sensitivity than tracking the frequency shifts of the LSPR peaks. Furthermore, single AuNCs with vertices exhibited higher RI sensitivity than single AuNSs of similar size in the homogeneous LSPR IFs. Therefore, we provided a deeper insight into the RI sensitivity of homogeneous LSPR IFs of AuNCs with vertices for their use in LSPR-based biosensors.

Highlights

Despite the remarkable advantages of localized surface plasmon resonance (LSPR)-based biosensors, they still have many fundamental limitations
The results indicate that tracking the homogeneous LSPR inflection points (IFs) of AuNCs with vertices can be effectively used to develop LSPR-based biosensors with high refractive index (RI) sensitivity
We demonstrated the significance of tracking the curvature shapes through homogeneous LSPR IFs near the resonance energy in various local RIs, rather than tracking their counterpart LSPR maximum peak shifts, for both AuNSs and AuNCs of similar size

Summary

Introduction

Despite the remarkable advantages of LSPR-based biosensors, they still have many fundamental limitations. It should be noted that alterations in the shape of the LSPR peak can have a negative effect on the sensing efficiency[26] To overcome these limitations, recent studies have, for example, improved the effectiveness by using lithographic methods, but there are some disadvantages such as the high processing cost and low yield[23]. Chen and co-workers reported a different approach that evaluates the changes in LSPR curvature of ensemble samples with respect to RI changes[23]. They showed that higher RI sensitivity was obtained in the inflection points (IFs) located at the long wavelength side (or low energy side) of the LSPR extinction peak[25]. The results indicate that tracking the homogeneous LSPR IFs of AuNCs with vertices can be effectively used to develop LSPR-based biosensors with high RI sensitivity

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Results

Conclusion