Plasmonic enhancement

In order to investigate this effect, ordered arrays of metallic nano-islands were fabricated on glass substrates by a process of natural lithography using monodisperse polystyrene nanospheres. The metal particle dimensions were tailored in order to tune the plasmon resonance wavelength to match the spectral absorption of the fluorophore. The fluorophore, Cy5 dye, which is widely used in optical immunoassays and has a medium quantum efficiency ( 0.3), was used in this preliminary study of the plasmonic enhancement effect. 

Pettinger B., Wenning U., Wetzel H., Surface-plasmon enhanced Raman-scattering frequency and angular resonance of Raman scattered-light from pyridine on Au, Ag and Cu electrodes, Surf. Sci. 1980 101 409-416. 

Robelek R, Stefani FD, Knoll W (2006) Oligonucleotide hybridization monitored by surface plasmon enhanced fluorescence spectroscopy with bio-conjugated core/shell quantum dots. Influence of luminescence blinking. Phys Status Solidi A-Appl Mater Sci 203 3468-3475... 

Park HJ, Vak D, Noh YY, Lim B, Kim DY (2007) Surface plasmon enhanced photoluminescence of conjugated polymers. Appl Phys Lett 90 161107... 

Apart from polymers and indicators, the beads can contain a variety of other components that improve their properties or provide additional functionalities. For example, addition of titanium dioxide nanoparticles significantly increases the brightness of the beads due to light scattering [5]. The plasmonic enhancement... 

Fan, G.-Q., et ah, Plasmonic-enhanced polymer solar cells incorporating solution-processable Au nanoparticle-adhered graphene oxide. Journal of Materials Chemistry, 2012. 22(31) ... 

Composite MIP nanomaterials are of increasing interest, since the inclusion in particular of inorganic additives into the MIP matrix provides additional useful properties, such as magnetic susceptibility, fluorescence, plasmonic enhancement, or simply an increased stability of the material. 

Metal nanoparticles have also been included into MIPs. Such particles can be used, for example, as nanoantennae for the enhancement of electromagnetic waves (plasmonic enhancement). It has been shown by He et al. [122] that a thin layer (20-120 nm) of testosterone-imprinted silica could be synthesized around 350 nm silver particles in a controlled way. The composite material showed specific binding of the testosterone target. Matsui et al. [123] reported a molecularly imprinted polymer with immobilized Au nanoparticles as a sensing material for spectrometry. The sensing mechanism is based on the variable proximity of the Au nanoparticles... 

Plasmon-Enhanced Heating Nanoparticles as Photothermal Agents... 

Figure 5.44 (a) General molecular structure of the porphyrin disulfides, PDSn, described by Ishida and Majima [76]. (b) Changes in the surface plasmon enhanced fluorescence spectra for the exchange reaction of a decane thiol SAM with a 50 mmol dm-31,2-dichloroethane solution of PDS10 (Xem = 725 nm Xex = 425 nm). From A. Ishida and T. Majima, /. Chem. Soc., Chem. Commun., 1299-1300 (1999). Reproduced by permission of The Royal Society of Chemistry... 

Stranik O, Nooney R, McDonagh C et al (2007) Optimization of nanoparticle size for plasmonic enhancement of fluorescence. Plasmonics 2 15-22... 

Chu L-Q, Forch R, Knoll W (2007) Surface-plasmon-enhanced fluorescence spectroscopy for DNA detection using fluorescently labeled PNA as DNA Indicator . Angew Chem Int Ed 46 4944-4947... 

Ghaemi HF, Thio T, Grupp DE, Ebbesen TW, Lezec HJ (1998) Surface plasmons enhance optical transmission through subwavelength holes. Phys Rev B 58 6779-6782... 

Krishnan A, Thio T, Kima TJ, Lezec FU, Ebbesen TW, Wolff PA, Pendry J, Martin-Moreno L, Garcia-Vidal FJ (2001) Evanescently coupled resonance in surface plasmon enhanced transmission. Opt Commun 200 1-7... 

Reilly TH, Chang SH, Corbman JD, Schatz GC, Rowlen KL (2007) Quantitative evaluation of plasmon enhanced Raman scattering from nanoaperture arrays. J Phys Chem C 111 1689-1694... 

One may be gullible to say that a small nanowire period is always desired to induce local plasmonic field enhancement, thereby strong sensitivity enhancement. What may really be critical is net nanowire or nano-groove width, i.e.,//t or ( f)A. In other words, even with a large nano wire period, one may excite LSPs efficiently if a fill factor is sufficiently small. There seems to exist a fill factor value at which local fields are maximally induced. Figure 4 presents resonance angles with and without a 1-nm thick 1,6-hexanedithiol (HOT) dielectric SAM as a VF is varied and shows enhanced plasmon momentum at ri = 50 nm and VF 0.8 and also at ri = 100 nm and VF 0.9, when nanowire gap is 10 nm in both cases [14]. In other words, absolute nanowire gap may be more important in plasmon enhancement than nanowire period. These trends have been reported in many near-held studies [15, 16]. 

Y. Zhang, K. Aslan, M. J. Previte, and C. D. Geddes. Metal-enhanced Singlet Oxygen Generation A Consequence of Plasmon Enhanced Triplet YifiXAs Journal of Fluorescence, 2007, 17, 345-349. 

Plasmonic en neering provides the flmdamentals for nanostructure fabrication exploiting the unique optical propolies of certain metals (mainly silver and gold) and advancing the development and applications of plasmon enhanced luminescence. Nanostructures can not only be fabricated to provide enhancement throughout the UV-Vis spectrum but also for near infiared excitation and emissions. 

Optimisation Of Plasmonic Enhancement Of Fluorescence For Optical Biosensor Applications... 

The detected fluorescence can be significantly enhanced, however, by exploiting the plasmonic enhancement which can occur when a metal nanoparticle (NP) is placed in the vicinity of a fluorescent label or dye [1-3]. This effect is due to the localised surface plasmon resonance (LSPR) associated with the metal NP, which modifies the intensity of the electromagnetic (EM) field around the dye and which, under certain conditions, increases the emitted fluorescence signal. The effect is dependent on a number of parameters such as metal type, NP size and shape, NP-fluorophore separation and fluorophore quantum efficiency. There are two principal enhancement mechanisms an increase in the excitation rate of the fluorophore and an increase in the fluorophore quantum efficiency. The first effect occurs because the excitation rate is directly proportional to the square of the electric field amplitude, and the maximum enhancement occurs when the LSPR wavelength, coincides with the peak of the fluorophore absorption band [4, 5]. The second effect involves an increase in the quantum efficiency and is maximised when the coincides with the peak of the fluorophore emission band [6]. 

Our work has focussed on two key areas which underpin the eventual exploitation of plasmonic enhancement features in fluorescence-based biosensors ... 

Establishment of synthetic and fabrication techniques which enable reproducible implementation of plasmonic enhancement principles in practical biochip systems and,... 

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