Actuated plasmonic nanohole arrays for sensing and optical spectroscopy applications.

Daria Kotlarek,Nestor Gisbert Quilis,Jiří Homola,Ulrich Jonas,Médéric Lequeux,Jiří Slabý,Jakub Dostálek,Marc Lamy De La Chapelle,Stefan Fossati,Frédéric Amiard,Priyamvada Venugopalan

doi:10.1039/d0nr00761g

Abstract

Herein, we report a new approach to rapidly actuate the plasmonic characteristics of thin gold films perforated with nanohole arrays that are coupled with arrays of gold nanoparticles. The near-field interaction between the localized and propagating surface plasmon modes supported by the structure was actively modulated by changing the distance between the nanoholes and nanoparticles and varying the refractive index symmetry of the structure. This approach was applied by using a thin responsive hydrogel cushion, which swelled and collapsed by a temperature stimulus. The detailed experimental study of the changes and interplay of localized and propagating surface plasmons was complemented by numerical simulations. We demonstrate that the interrogation and excitation of the optical resonance to these modes allow the label-free SPR observation of the binding of biomolecules, and is applicable for in situ SERS studies of low molecular weight molecules attached in the gap between the nanoholes and nanoparticles.

Highlights

Daria Kotlarek,‡a Stefan Fossati,a Priyamvada Venugopalan,§a,b Nestor Gisbert Quilis,a Jiří Slabý,c Jiří Homola, c Médéric Lequeux,d Frédéric Amiard,e Marc Lamy de la Chapelle,e Ulrich Jonasf and Jakub Dostálek *a
We developed a method to prepare a nanostructure geometry that combines thin gold films perforated with nanohole arrays (NHAs) and arrays of gold NP, which are suspended in a thin layer of a poly(N-isopropyl acrylamide)-based hydrogel
It is worth noting that this thermo-responsive hydrogel cushion allowed the controlled opening and closing of the nanohole arrays of pores, and switching to the open state was accompanied by the rapid diffusion of water, which drags contained biomolecules through the pores, where a plasmonic hotspot occurs

Summary

Introduction

Daria Kotlarek,‡a Stefan Fossati,a Priyamvada Venugopalan,§a,b Nestor Gisbert Quilis,a Jiří Slabý,c Jiří Homola, c Médéric Lequeux,d Frédéric Amiard,e Marc Lamy de la Chapelle,e Ulrich Jonasf and Jakub Dostálek *a. To distinguish between the diffraction coupling to the dispersive PSP modes (traveling along the gold film) and non-dispersive LSP resonances (supported by the pores in the NHA + NP nanostructure), transmission spectra were measured via collimated beam impinging on the NHA + NP structure at angles in the range of θ = 0° to 25°.

Results

Conclusion