Influence of silver grain size, roughness, and profile on the extraordinary fluorescence enhancement capabilities of grating coupled surface plasmon resonance

Abstract

Since the development of fluoroimmunoassays, researchers have sought a method of substantially enhancing fluorescence intensity to extend the limits of detection to new levels of sensitivity. Surface plasmon resonance (SPR) and metal enhanced fluorescence has long been a topic of research and has led to the development of prism-and grating-based SPR systems. However, with the wide coupling range and ease of exciting SPR on plasmonic gratings with a simple microscope objective, they have tremendous potential for revolutionizing the fields of plasmonics, fluorescence, and sensors. In an effort to better understand the influence of grating profile and metal film properties on the extraordinary fluorescence enhancement capabilities of plasmonic gratings, a novel microcontact printing process and different metal deposition techniques were used to fabricate silver gratings with varying grain diameters, roughnesses, heights, and duty cycles using thermal evaporation and RF sputtering. The resulting plasmonic gratings exhibited fluorescence enhancements up to 116Â that of dye-coated glass slides using an epifluorescence microscope, much higher than more expensive prism-based SPR systems. This silver grating represents an extraordinary opportunity to quickly and easily enhance fluorescence and widen the detection limits of common fluorescence based assays with little to no equipment modification.

Reproducible Enhancement of Fluorescence by Bimetal Mediated Surface Plasmon Coupled Emission for Highly Sensitive Quantitative Diagnosis of Double‐Stranded DNA

“…The metal structure that would support surface plasmons at a dye emission wavelength (λ em ) also couples with dye molecules for enhanced rate of radiative decay . Plasmonic dispersion relation dominates a directional pattern of the radiation at λ em , resulting in SNR enhancement additionally with photobleaching suppressed . Various plasmonic nanostructures that support surface plasmon resonance (SPR) or localized surface plasmon resonance (LSPR) have been demonstrated for fluorescence enhancement by metal nanostructures such as silver nanoparticles, continuous metal films of nanometer scale thickness, silver island films on metallic mirrors, and roughened surface of thin metal films …”

Super-Resolution Light Microscopy Using Plasmonic Gratings

“…Because of the inherently Grating coatings. The microcontact lithography process for making PMSSQ gratings from profiles stored on DVDs is described in detail in our previous publications [20][21][22][23][24][25]28]. This process can be used to fabricate PMSSQ gratings on both microscope slides and silicon wafers.…”

Fluorescence Enhancement Using Bimetal Surface Plasmon-Coupled Emission from 5-Carboxyfluorescein (FAM)

“…One efficient solution for SNR elevation is to use metallic structures brought in nanoscale proximity to dye molecules, for luminescence enhancement, which is referred to as the metal-enhanced fluorescence (MEF), in a broad sense [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Particularly, in SPR, the resonance state that results from the coherently phase-matched coupling between a collective oscillation mode of conduction electrons and a transverse magnetic (TM) mode of the electromagnetic wave (at a metal–dielectric interface), has been employed to effectively demonstrate fluorescence enhancement and photostability [ 32 , 33 ]. It is known that surface plasmons can couple with fluorescent dye molecules to enhance the dye excitation rate, at an excitation wavelength (λ ex ) [ 34 ].…”