Surface plasmon field-enhanced fluorescence spectroscopy

Surface Plasmon Field-Enhanced Fluorescence Spectroscopy 

These features make SPFS to be surface sensitive and compatible to modern biosensor platforms. In the same category, total internal reflection fluorescence 

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Alternatively, various analytical methods based on SPR phenomenon have been developed, including surface plasmon field-enhanced Raman scattering (SERS) [7], surface plasmon field-enhanced fluorescence spectroscopy (SPFS) [8-11], surface enhanced second harmonic generation (SHG) [12], surface enhanced infrared absorption (SEIRA) [13], surface plasmon field-enhanced diffraction spectroscopy (SPDS) [14-18], Most of these methods take advantage of the greatly enhanced electromagnetic field of surface plasmon waves, in order to excite a chromophoric molecule, e.g., a Raman molecule or a fluorescent dye. Therefore, a better sensitivity is expected. 

Surface Plasmon Field-Enhanced Fluorescence Spectroscopy... 

Liebermann, T., and Knoll, W. (2000). Surface-plasmon field-enhanced fluorescence spectroscopy. Colloid and Surfaces A. Physicochemical and Engineering Aspects 171 115-130. 

Ekgasit, S., Thammacharoen, C., Yu, F., and Knoll, W. (2004). Evanescent Field in Surface Plasmon Resonance and Surface Plasmon Field-Enhanced Fluorescence Spectroscopies./Ina/. Chem. 76 2210-2219. 

In an attempt to overcome this limit of detection we recently introduced surface plasmon field-enhanced fluorescence spectroscopy (SPFS) following an earlier report liy Attridge et al. The basic principle of this approach combines the excitation of a surface plasmon mode as an interfacial light source with the well-established detection schemes of fluorescence spectroscopy the resonantly excited surface plasmon waves excite chromophores that are attached to the analyte either chemically or by genetic engineering techniques. The emitted fluorescence photons are then monitored and analyzed in the usual way to give information about the behavior of the analyte itself. 

Yu YM, Feng CL, Caminade AM, Majoral JP, Knoll W (2009) The detection of DNA hybridization on phosphorus dendrimer multilayer films by surface plasmon field enhanced-fluorescence spectroscopy. Langmuir 25 13680-13684... 

The electromagnetic field enhancement provided by nanostructure plasmonics is the key factor to manipulate the quantum efficiency. However, as it is illustrated in the unified theory of enhancement, since both the radiative and non-radiative rates of the molecular systems are affected by proximity of the nanostructure, the tuning has to be done on a case by case basis. In addition, there are factors due to molecule-metal interactions and molecular orientation at the surface causing effects that are much more molecule dependent and as are much more difficult to predict. Given the fact that fluorescence cross sections are the one of the highest in optical spectroscopy the analytical horizon of SEF or MEF is enormous, in particular in the expanding field of nano-bio science. 

This approach has common features with the well-known total internal reflection fluorescence (TIRF) spectroscopy that is also a surface-sensitive and surface-specific detection method, but lacks, however, the enormous enhancement of the optical fields that can be obtained at resonant excitation of a surface plasmon wave which is responsible for the substantial sensitivity enhancement in bio-affinity studies. 

Nanoporous platforms recently have found utility in the fields of plasmonics and optical detection. Nanoporous gold fllms and metallic-coated nanopores - have been applied to techniques like surface-plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS). Additionally, nanoporous metal has been demonstrated to enhance single-molecule fluorescence intensity of immobilized fluorophores due to the enhanced localized plasmon field present within the nanopores. Optically transparent alumina membranes have been developed and found utility as optical biosensors. Additionally, nanoporous gold has been demonstrated to optically detect Hg + ions at concentrations smaller than parts per trillion. A fiber-optic ultrasound generator has been developed from the excitation of gold nanopores with a nanosecond laser. ... 

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