Tailored Plasmonic Gratings for Enhanced Fluorescence Detection and Microscopic Imaging

Abstract

The ability to precisely control the pattern of metallic structures at the micro‐ and nanoscale for surface plasmon coupling has been demonstrated to be essential for signal enhancement in fields such as fluorescence and surface‐enhanced Raman scattering. In the present study, a series of silver coated gratings with tailored duty ratio and depth and a periodical pitch of 400 nm are designed and implemented. The influence of the grating profile on plasmonic properties and the corresponding enhancement factor are investigated by angular scanning measurement of reflectivity and fluorescence intensity and by finite difference time domain simulation. The application of the substrate in the enhanced fluorescence imaging detection of labeled protein is also investigated. This substrate has a wide range of potential applications in areas including biodiagnostics, imaging, sensing, and photovoltaic cells.

Recent Progress on Plasmon-Enhanced Fluorescence

“…In general, due to the existence of a mismatch in wave vector momentum of the SPPs and the incident light, the excitation of SPPs on a flat continual metal surface is difficult to realise [27]. So it is difficult to obtain the potential plasmonic coupling as well as efficiency of the fluorescence enhancement effect on the metal substrate with flat morphology [30]. It is shown that the mismatch can be overcome by introduction of an external periodical metal surface such as gratings, nanohole arrays, nanocaps arrays, and so on.…”

“…As a result, the moderated diffraction on periodically corrugated metallic surfaces provides an alternative method for simultaneous SPP-enhanced excitation at λ ab and extraction of SPP-driven emission of fluorescence light at λem. By fabricating a series of tailored silver plasmonic grating nanostructure, Tawa systematically investigated the relationship between the grating parameters (depth and duty ratio) and the fluorescence enhanced effect [30,31], and found that at a depth of 20 nm and duty ratio equal to 0.43, the fabricated grating substrate achieves optimal fluorescence enhancement. It is found that the fluorescence enhancement mechanisms from grating arise from both the SPP-enhanced absorption and SPCE.…”

H-Shape Plasmonic Metasurface as Refractive Index Sensor

“…Plasmonic metasurfaces have also been explored for the determination of effective refractive index of a surrounding medium, for molecular detection using surface-enhanced Raman scattering (SERS) technique as well as metal or surface-enhanced fluorescence (SEF) process [4][5][6][7][8][9][10][11][12]. In all these processes, significant contribution comes from the highly enhanced electromagnetic near-fields localized around the sharp edges of metallic nanostructures.…”

Nanomaterial‐based advanced immunoassays

“…In another work, micro‐ and nanoscale patterns of different metals are fabricated based on a combination of lithographic techniques and galvanic displacement reactions to achieve highly sensitive fluorescent immunoassay in an array format 43. Recently, 1D grating and 2D nanohole array coated with silver thin film are prepared and demonstrate strong fluorescence enhancement, respectively 44,45. Ag/SiO 2 core‐shell nanoparticles are prepared as versatile enhancement tags to intensify fluorescence signals of any fluorophores attached on the outer silica 46.…”