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Localized Surface Plasmon Resonance (localized + surface_plasmon_resonance)

Distribution by Scientific Domains
Polymers and Materials Science75%

Selected Abstracts

Nanoarrays: Cooperative Near-Field Surface Plasmon Enhanced Quantum Dot Nanoarrays (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Mater.
Abstract Fluorescence from quantum dots (QDs) sandwiched between colloidal gold nanoparticles and lithographically created metal nanoarrays is studied using engineered peptides as binding agents. For optimized structures, a 15-fold increase is observed in the brightness of the QDs due to plasmon-enhanced fluorescence. This enhanced brightness is achieved by systematically tuning the vertical distance of the QD from the gold nanoparticles using solid-specific peptide linkers and by optimizing the localized surface plasmon resonance by varying the geometric arrangement of the patterned gold nanoarray. The size and pitch of the patterned array affect the observed enhancement, and sandwiching the QDs between the patterned features and colloidal gold nanoparticles yields even larger enhancements due to the increase in local electromagnetic hot spots induced by the increased surface roughness. The use of bifunctional biomolecular linkers to control the formation of hot spots in sandwich structures provides new ways to fabricate hybrid nanomaterials of architecturally induced functionality for biotechnology and photonics. [source]

Cooperative Near-Field Surface Plasmon Enhanced Quantum Dot Nanoarrays

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Kirsty Leong
Abstract Fluorescence from quantum dots (QDs) sandwiched between colloidal gold nanoparticles and lithographically created metal nanoarrays is studied using engineered peptides as binding agents. For optimized structures, a 15-fold increase is observed in the brightness of the QDs due to plasmon-enhanced fluorescence. This enhanced brightness is achieved by systematically tuning the vertical distance of the QD from the gold nanoparticles using solid-specific peptide linkers and by optimizing the localized surface plasmon resonance by varying the geometric arrangement of the patterned gold nanoarray. The size and pitch of the patterned array affect the observed enhancement, and sandwiching the QDs between the patterned features and colloidal gold nanoparticles yields even larger enhancements due to the increase in local electromagnetic hot spots induced by the increased surface roughness. The use of bifunctional biomolecular linkers to control the formation of hot spots in sandwich structures provides new ways to fabricate hybrid nanomaterials of architecturally induced functionality for biotechnology and photonics. [source]

Dynamic Tuning of Plasmon,Exciton Coupling in Arrays of Nanodisk,J-aggregate Complexes

ADVANCED MATERIALS, Issue 32 2010
Yue Bing Zheng
Dynamic tuning of plasmon,exciton resonant coupling in arrays of nanodisk,J-aggregate complexes is demonstrated. The angle-resolved spectra of an array of bare gold nanodisks exhibit continuous shifting of localized surface plasmon resonance. This characteristic enables the production of real-time, controllable spectral overlap between molecular resonance and plasmonic resonance. The resonant interaction strength as a function of spectral overlap is explored and the coupling strength changes with the incident angle of a probe light, in accord with simulations based on coupled dipole approximation method. [source]

Surface-enhanced Raman sensors: early history and the development of sensors for quantitative biowarfare agent and glucose detection

JOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005
Christy L. Haynes
Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for the sensitive and selective detection of low-concentration analytes. This paper includes a discussion of the early history of SERS, the concepts that must be appreciated to optimize the intensity of SERS and the development of SERS-based sensors. In order to achieve the lowest limits of detection, both the relationship between surface nanostructure and laser excitation wavelength, as well as the analyte/surface binding chemistry, must be carefully optimized. This work exploits the highly tunable nature of nanoparticle optical properties to establish the first set of optimization conditions. The SERS enhancement factor, EFSERS, is optimized when the energy of the localized surface plasmon resonance (LSPR) lies between the energy of the excitation wavelength and the energy of the vibrational band of interest. With the narrow LSPRs used in this work, it is straightforward to achieve EFSERS , 108. These optimization conditions were exploited to develop SERS-based sensors for two important target molecules: a Bacillus anthracis biomarker and glucose in a serum protein mixture. Using these optimized film-over-nanosphere surfaces, an inexpensive, portable Raman spectrometer was used successfully to detect the infectious dose of Bacillus subtilis spores with only a 5-s data collection. The biomarker used to detect the Bacillus subtilis spores binds irreversibly to SERS substrates, whereas other important biomolecules, such as glucose, do not have any measurable binding affinity to a bare silver surface. To overcome this difficulty, a biocompatible partition layer was self-assembled on the SERS substrate before exposure to the analyte solution. Using the partition layer approach to concentrate glucose near the SERS-active substrate, physiological glucose concentrations can be detected even in the presence of interfering serum proteins. Copyright © 2005 John Wiley & Sons, Ltd. [source]