Surface Plasmon Coupled Fluorescence in the Ultraviolet and Visible Spectral Regions Using Zinc Thin Films

Nanoplasmonic Sensor Based on Surface Plasmon-Coupled Emission: Review

The surface plasmon resonance (SPR) technique is a powerful method to detect chemical molecules. Fluorescent spectroscopy is a subject of great interest in the field of material science and biology. Recently, some optical sensors, based on plasmonic properties of nanomaterial, were introduced to enhance the investigation of the interaction of molecular while detecting the low concentration of molecular. The surface plasmon-coupled emission (SPCE) technique is a merit and accurate method to evaluate the interaction of nanomaterials and molecular. SPCE is based on fluorescence properties of interest molecule, and the surface plasmon enhances the fluorescence signal. According to SPR theory, the condition of excitation of fluorophore could be used in obtaining the SPCE signal. SPCE can be used to detect toxic chemicals and investigate the human molecular. In this review, the theory, experimental setup, condition of SPCE, and role of metal nanoparticles in SPCE were reviewed. In the end, the application of SPCE was presented for detection and monitoring the chemical material, heavy metal, and biologic molecules.

Enhancement of the Chemiluminescence Response of Enzymatic Reactions by Plasmonic Surfaces for Biosensing Applications

We report the enhancement of chemiluminescence response of horseradish peroxidase (HRP) in bioassays by plasmonic surfaces, which are comprised of (i) silver island films (SIFs) and (ii) metal thin films (silver, gold, copper, and nickel, 1 nm thick) deposited onto glass slides. A model bioassay, based on the interactions of avidin-modified HRP with a monolayer of biotinylated poly(ethylene-glycol)-amine, was employed to evaluate the ability of plasmonic surfaces to enhance chemiluminescence response of HRP. Chemiluminescence response of HRP in model bioassays were increased up to ~3.7-fold as compared to the control samples (i.e. glass slides without plasmonic nanoparticles), where the largest enhancement of the chemiluminescence response was observed on SIFs with high loading. These findings allowed us to demonstrate the use of SIFs (high loading) for the detection of a biologically relevant target protein (glial fibrillary acidic protein or GFAP), where the chemiluminescence response of the standard bioassay for GFAP was enhanced up to ~50% as compared to bioassay on glass slides.

Modulation of surface plasmon coupled emission (SPCE) by a pulsed magnetic field

The SPCE was modulated by a magnetic field through the interaction between plasmon and magnetic field.

Optical antenna design for fluorescence enhancement in the ultraviolet

Through rational design, we compare the performance of three plasmonic antenna structures for UV fluorescence enhancement. Among the antenna performance metrics considered are the local increase in excitation intensity and the increase in quantum efficiency, the product of which represents the net fluorescence enhancement. With realistic structures in aluminum, we predict that greater than 100× net enhancement can be obtained.

Surface plasmon-coupled emission: what can directional fluorescence bring to the analytical sciences?

Surface plasmon-coupled emission (SPCE) arose from the integration of fluorescence and plasmonics, two rapidly expanding research fields. SPCE is revealing novel phenomena and has potential applications in bioanalysis, medical diagnostics, drug discovery, and genomics. In SPCE, excited fluorophores couple with surface plasmons on a continuous thin metal film; plasmophores radiate into a higher-refractive index medium with a narrow angular distribution. Because of the directional emission, the sensitivity of this technique can be greatly improved with high collection efficiency. This review describes the unique features of SPCE. In particular, we focus on recent advances in SPCE-based analytical platforms and their applications in DNA sensing and the detection of other biomolecules and chemicals.

Directional, Broad, and Fixed Angle Surface Plasmon Coupled Fluorescence from Iron Thin Films

Fixed angle surface plasmon coupled fluorescence (SPCF) from iron thin films is demonstrated for the first time. The optimum thickness of the iron thin films was determined to be 15 nm using Fresnel calculations. The angles of minimum reflectivity for light at 496-814 nm were predicted to occur at a fixed and broad range of angles of 60-70°. Experimental corroboration of these predictions were undertaken by employing fluorescein isothiocyanate (emission peak at 517 nm), rhodamine B (580 nm), zinc phthalocyanine (710 nm), and IR 780 dye (814 nm). SPCF emission from all four fluorophores was directional, p-polarized, and observed at a fixed angle of ∼65°.

Directional surface plasmon coupled luminescence for analytical sensing applications: which metal, what wavelength, what observation angle?

The ability of luminescent species in the near-field to both induce and couple to surface plasmons has been known for many years, with highly directional emission from films (Surface Plasmon Coupled Luminescence, SPCL) facilitating the development of sensitive near-field assay sensing platforms, to name but just one application. Because of the near-field nature of the effect, only luminescent species (fluorescence, chemiluminescence and phosphorescence) within a few hundred nanometers from the surface play a role in coupling, which in terms of biosensing, provides for limited penetration into optically dense media, such as in whole blood. Another attractive feature is the highly polarized and angular dependent emission which allows both fixed angle and wavelength dependent emission angles to be realized at high polarization ratios. In this paper, a generic procedure based on theoretical Fresnel calculations, which outlines the step-by-step selection of an appropriate metal for SPCL applications is presented. It is also shown that 11 different metals have differing properties in different spectral regions and offer either fixed angle or wavelength-dependent angular shifts in emission. In addition, it is shown that both chemiluminescence and phosphorescence can also be observed in a highly directional manner similar to coupled fluorescence.

Nanoparticle strategies for enhancing the sensitivity of fluorescence-based biochips

This article describes strategies for achieving fluorescence enhancement in optical biochips. Two strategies are discussed: plasmonic enhancement, which is due to the localized surface plasmon resonance of metal nanostructures that are adjacent to the fluorescent labels in optical immunoassays; and the use of high-brightness silica nanoparticles as enhanced labels. We present a review of the state-of-the-art in both areas, including synthesis techniques for the metal and silica nanoparticles and the use of the nanoparticles in optical immunoassays. Data are presented that highlight the key design parameters which influence the level of enhancement and model assay data are presented that illustrate potential enhancements in assay performance.