Fluorescence Enhancement via Dual Coupling of Dye Molecules with Silver Nanostructures

Abstract

We demonstrate the enhancement of fluorescence emitted from dye molecules coupled with two surface plasmons, i.e., silver nanoparticles (AgNPs)-induced localized surface plasmons (LSP) and thin silver (Ag) film supported surface plasmons. Excitation light is illuminated to a SiO2 layer that contains both rhodamine 110 molecules and AgNPs. AgNPs enhances excitation rates of dye molecules in their close proximity due to LSP-induced enhancement of local electromagnetic fields at dye excitation wavelengths. Moreover, the SiO2 layer on one surface of which a 50 nm-thick Ag film is coated for metal cladding (air on the other surface), acts as a waveguide core at the dye emission wavelengths. The Ag film induces the surface plasmons which couple with the waveguide modes, resulting in a waveguide-modulated version of surface plasmon coupled emission (SPCE) for different SiO2 thicknesses in a reverse Kretschmann configuration. We find that varying the SiO2 thickness modulates the fluorescent signal of SPCE, its modulation behavior being in agreement with the theoretical simulation of thickness dependent properties of the coupled plasmon waveguide resonance. This enables optimization engineering of the waveguide structure for enhancement of fluorescent signals. The combination of LSP enhanced dye excitation and the waveguide-modulated version of SPCE may offer chances of enhancing fluorescent signals for a highly sensitive fluorescent assay of biomedical and chemical substances.

Multiarchitecture-Based Plasmonic-Coupled Emission Employing Gold Nanoparticles: An Efficient Fluorescence Modulation and Biosensing Platform

“…In contrast, the spin-coating method more easily builds different coupling structures without complex modification, which is beneficial for constructing and studying new plasmonic systems. Many nanomaterials and composites have been utilized in SPCE systems based on this spin-coating method, such as low-dimensional materials, metallic nanoparticles and composites, and Soret colloids, ,,,,, to obtain new plasmonic systems with unique optical emission enhancement. Herein, the enhancement effect based on the spin-coating substrate was also studied.…”

“…Gold nanoparticles (AuNPs) possess particular physical and chemical properties, such as high stability, good compatibility, and easy surface functionalization, which make them ideal materials for a wide range of optical, chemical, biological, and clinical applications. − Among the different optical materials, AuNPs are the most popular candidate for the development of systems with high sensitivity and detection efficiency. , When metallic NPs interact with light, resonance energy coupling known as localized surface plasmon resonance (LSPR) can be evoked to create an intense electromagnetic (EM) field. LSPR occurs due to the energy transfer from the excited light to the collective oscillation of free electrons around the nanoparticles, which leads to a strong absorption of optical energy. − The absorption peak depends on the size, shape, aggregation state, and dielectric environment . Nanoscale contacts between metal structures to form nanogap junctions are crucial plasmonic geometries; therefore, the close junctions between metallic nanoparticles and continuous films are an effective plasmon modulation system that can induce intense interactions between localized and propagating surface plasmons to generate “hot-spots” along with enormous enhancement of the EM field under certain conditions. − It is well known that this phenomenon works not only to optimize detection methods but also to build new plasmon-based enhanced systems. − …”

Optical Sensing of Toxic Cyanide Anions Using Noble Metal Nanomaterials

“…Metal nanoparticles have been involved in optical sensing platforms, including those based on colorimetry [ 27 , 28 ], surface plasmon resonance [ 41 , 42 , 43 , 44 ], fluorescence [ 45 , 46 , 47 ], RS [ 48 ], and SERS tactics [ 49 , 50 ]. These sensing devices have produced reasonably good sensitivity in detecting analytes with adequate specificity, whereas the high reproducibility of the sensor signals remains a challenge due to limited control over the uniformity of nanoparticle size to date.…”

Adamantane Three-Dimensional Porous Organic Framework as a Fluorescence Sensor for Rapid Determination of Tetracycline in Aquatic Products

“…Although these methods have high sensitivity and accuracy, they often suffer from time-consuming, complicated experimental processes or the requirement of expensive equipment. Fluorescence methods have attracted widespread attention due to their advantages of a fast response, high sensitivity and simple equipment [8][9][10]. The fluorescence material plays an important role in the sensitivity, selectivity and sensing speed of a fluorescence method [11,12].…”