Sensing Characteristics of NIR Localized Surface Plasmon Resonances in Gold Nanorings for Application as Ultrasensitive Biosensors

The optical responses of 75−150 nm diameter gold nanorings to changes in local refractive index have been quantified by near-infrared extinction spectroscopy and compared to DDA calculations and an analytical approach. The “bulk” refractive index sensitivities of gold nanorings are substantially (&g...

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Bibliographic Details
Published in:Nano letters 2007-05, Vol.7 (5), p.1256-1263
Main Authors: Larsson, Elin M, Alegret, Joan, Käll, Mikael, Sutherland, Duncan S
Format: Article
Language:English
Subjects:
Biosensing Techniques
Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Exact sciences and technology
Fullerenes and related materials
General equipment and techniques
Gold - chemistry
Infrared and raman spectra and scattering
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Nanostructures
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
Physics
Sensitivity and Specificity
Sensors (chemical, optical, electrical, movement, gas, etc.)
remote sensing
Spectroscopy, Near-Infrared - methods
Surface and interface electron states
Surface Plasmon Resonance - methods
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Summary:The optical responses of 75−150 nm diameter gold nanorings to changes in local refractive index have been quantified by near-infrared extinction spectroscopy and compared to DDA calculations and an analytical approach. The “bulk” refractive index sensitivities of gold nanorings are substantially (>5 times) larger than those of nanodisks with similar diameters. Nanorings retain a significantly larger sensitivity than nanodisks at the same spectral position, demonstrating a clear shape dependence that may correlate to a systematic difference in the influence of the dielectric substrate. The nanoring bulk refractive index sensitivity scales linearly with plasmon peak position. The spectral sensitivity to thin films of alkanethiols gave a shift of ∼5.2 nm/CH2 unit while bulk sensitivities as high as 880 nm/RIU were observed, the highest such reported sensitivities. Both bulk and thin dielectric film sensitivities correlated well with theory. Real-time label-free monitoring of protein binding via molecular recognition was demonstrated.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl0701612