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Title: Nanosphere lithography fabricated nanostructures for use in surface-enhanced Raman scattering biosensing applications
Author: Gibson, Kirsty
ISNI:       0000 0004 2744 1500
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2012
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The use of plasmonic nanostructures in sensing applications has increased in recent years owing to improved fabrication methods. Reports in the literature have highlighted the great potential of film-over nanosphere (FON) and nanotriangle surfaces as sensitive and reproducible Surface-Enhanced Raman Scattering (SERS) substrates. The relationship between the physical and optical properties of nanostructured arrays is of great importance and it has a significant influence on the SERS enhancement exhibited by the arrays. However, there has been no comparative study on the plasmonic and Raman properties of closely related FON and nanotriangle substrates. This research details a systematic investigation into the origin of SERS enhancement in a series of nanostructures fabricated via modified nanosphere lithography (NSL). The symbiotic relationship between SERS and plasmonics was exploited by using SERS to probe and evaluate the nanostructured plasmonic surfaces. The relationship between the physical and optical properties of the nanostructures was investigated to understand and determine the optimal structures for use in SERS analysis. The optimal substrates identified for every series investigated were not FON or nanotriangle arrays but instead the closely related film-over etched nanosphere (FOEN) and nanohole arrays which were the result of an etching step in the fabrication process. The transition between nanotriangle and nanohole was studied and the localisation of hot-spots on the structures was identified. Experimental SERS false-colour images showed that in nanotriangle arrays, the electric field was concentrated at the point at which two triangle apexes met. In nanohole arrays, the electric field was greatest on the metal lattice that surrounds the holes. As the diameter of the nanoholes decreased, the electric field was located around the rim of the holes and in nanohole arrays with very small diameters the electric field was concentrated in the centre of the hole. The experimental results were in good agreement with theoretical predications. Nanohole arrays that were shown to have high SERS activity were used in a proof-of-concept SERS sensing study resulting in the detection of labelled Streptavidin at nanomolar concentrations. This method was then applied to a real-life system to probe the interaction of Aurora A with IKKβ peptides.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available