Plasmon-Enhanced Fluorescence Biosensors: a Review

Abstract

Surfaces of metallic films and metallic nanoparticles can strongly confine electromagnetic field through its coupling to propagating or localized surface plasmons. This interaction is associated with large enhancement of the field intensity and local optical density of states which provides means to increase excitation rate, raise quantum yield, and control far field angular distribution of fluorescence light emitted by organic dyes and quantum dots. Such emitters are commonly used as labels in assays for detection of chemical and biological species. Their interaction with surface plasmons allows amplifying fluorescence signal (brightness) that accompanies molecular binding events by several orders of magnitude. In conjunction with interfacial architectures for the specific capture of target analyte on a metallic surface, plasmon-enhanced fluorescence (PEF) that is also referred to as metal-enhanced fluorescence (MEF) represents an attractive method for shortening detection times and increasing sensitivity of various fluorescence-based analytical technologies. This review provides an introduction to fundamentals of PEF, illustrates current developments in design of metallic nanostructures for efficient fluorescence signal amplification that utilizes propagating and localized surface plasmons, and summarizes current implementations to biosensors for detection of trace amounts of biomarkers, toxins, and pathogens that are relevant to medical diagnostics and food control.

Recent Progress on Plasmon-Enhanced Fluorescence

“…Largely enhancement of the local electromagnetic (EM) field induced by surface plasmon resonance (SPR), which plays an important role in studying SES, including PEF and surface-enhanced Raman scattering (SERS), have the focus of discussions [10][11][12][13]. It is found that the characteristic of SPR (position and intensity) are critically dependent upon the geometrical parameter of the nanostructures, such as the size, shape, as well as the the composition of the nanostructure, and the dielectric constant of the surrounding environment [15][16][17][18].…”

“…Particularly, better understanding of coupling and interconversion mechanism among free electrons, surface plasmon, photons, and fluorophores based on metal substrate with various shape configurations in PEF effect still should be highlighted [10,11,20]. In this review, we focus on the recent advancement of the effect of plasmonic nanostructures towards PEF.…”

Surface plasmon-enhanced fluorescence on Au nanohole array for prostate-specific antigen detection

“…1 This phenomenon has been demonstrated by tremendous applications on chemical and biological sensors. [2][3][4][5][6] Highly enhanced local electromagnetic fields created by the resonantly pumped plasmonic nanostructures result in greatly increased incident light absorption and enhanced emitter excitation, supporting surface-enhanced spectroscopies including surface-enhanced Raman scattering, 7,8 surface-enhanced infrared spectroscopy, [9][10][11] and surface plasmon-enhanced fluorescence (SPFS). [12][13][14] Surface plasmons (SPs) with field E SP excited by an incoming light E 0 can enhance fluorophore excitation rate and Raman scattering by factors up to |E sp /E 0 | 2 and |E sp /E 0 | 4 , respectively.…”

Mid-IR optical properties of silicon doped InP

“…Plasmons can be excited by exposing subwavelength conductive particles to an external electromagnetic field, resulting in localized plasmon-polaritons (LPP) or by coupling the external field to the oscillating charges near the surface of the material, resulting in a highly confined surface wave propagating along the interface between the conductive and dielectric media, known as surface plasmon-polaritons (SPP) [1]. High confinement of this enhanced field provides higher local optical density of states and leads to applications such as plasmonenhanced photovoltaics [2], biosensing [3], Raman spectroscopy [4] and photocatalysis [5]. Furthermore, SPP's enable subwavelength spatial confinement of light, due to their dispersion properties.…”