EOT or Kretschmann configuration? Comparative study of the plasmonic modes in gold nanohole arrays

Abstract

The debate is still ongoing on the optimal mode of interrogation for surface plasmon resonance (SPR) sensors. Comparative studies previously demonstrated that nanoparticles exhibiting a localized SPR (LSPR) have superior sensitivity to molecular adsorption processes while thin Au film-based propagating SPR is more sensitive to bulk refractive index. In this paper, it is demonstrated that nanohole arrays (1000 nm periodicity, 600 nm diameter and 125 nm depth), which support both LSPR and propagating SPR modes, exhibited superior sensitivity to bulk refractive index and improved detection limits for IgG sensing by using the Kretschmann configuration. The greater sensitivity to IgG detection in the Kretschmann configuration was obtained despite the shorter penetration depth of nanohole arrays excited in the enhanced optical transmission (EOT) configuration. The decay length of the electromagnetic field in EOT mode was estimated to be approximately 140 nm using a layer-by-layer deposition technique of polyelectrolytes (PAH and PSS) and was confirmed with 3D FDTD simulations, which was lengthen by almost a factor of two in the Kretschmann configuration. Spectroscopic data and field depth were correlated with RCWA and FDTD simulations, which were in good agreement with the experimental results. Considering these analytical parameters, it is advantageous to develop sensors based on nanohole arrays in the Kretschmann configuration of SPR.

Tuning the 3D plasmon field of nanohole arrays

“…A K d of 250 nM was calculated with this sensor, which is close to the value we determined in SPR (92 nM) and the detection limit was similar to SPR sensing in the Kretschmann conguration. 35 The high surface sensitivity of nanohole arrays with large incident angle and periodicity is very promising for the future development of biosensors.…”

“…Nanohole array substrates were fabricated by modied nanosphere lithography as previously described 35 and summarized in the ESI. † Unless otherwise stated, the nanohole arrays were made of 120 nm of gold, with 820 nm periodicity and 500 nm hole diameter.…”

“…The materials and methods involving the layer by layer polyelectrolyte deposition technique and biosensing of IgG are reported elsewhere. 35 The IgG biodetection was performed with a SAM of 16-MHA for the 820 nm periodicity and 3-MPA-HHHDD-OH peptide for the 1000 nm periodicity, using a previously described protocol. 36 SERS A 4-nitrobenzenethiol (4-NBT) monolayer was formed on the gold nanohole arrays by immersing the samples overnight in a 10 mM solution of 4-NBT in DMF.…”

Universal sensitivity of propagating surface plasmon resonance in nanostructure arrays

“…For instance, a nanohole array has been used in the configuration of attenuated total reflection [19]. In the oblique incidence, much more in-plane momentum of incident light is coupled to SPs in comparison to the case of normal incidence.…”

Recent advances in plasmonic nanostructures for sensing: a review

“…110,108 This tunability for a particular application of interest allows for dramatic increases in SPR sensitivity. 107,[118][119][120] Although the tunability of such nanoarrays in gold is limited to the NIR and longer wavelength region of the visible (i.e., ∼500 nm or greater), a variation of these nanoslit and nanohole arrays, known as nanotriangle arrays [see Fig. 8(f)], 107 has demonstrated the ability to further expand the range of LSPR wavelengths achievable simply by altering the structure.…”