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Proceedings Paper

The effect of design parameters of metallic substrate on the reproducibility of SERS measurement for biosensing
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Paper Abstract

A successful detection of inherently weak Raman signal from molecules is possible with giant enhancement of signal by the process of surface-enhanced Raman scattering (SERS). The SERS-induced enhancement is typically achieved when the molecules adsorbed onto the surface of a noble-metal substrate with nanometric roughness. Such SERS-substrate could be economically fabricated by convective assembly of polystyrene beads followed by metal deposition. The characterization of mono-metallic substrate showed that the SERS enhancement factor increases with increasing thickness of Ag or Au, with Ag-substrate giving the greatest SERS enhancement. However, the formation of silver oxide layer could reduce the shelf-life of the Ag-substrate. Alternatively, Au is also used as the coating material owing to its chemical inertness and biocompatibility. Despite the decent enhancement of the Au-substrate, Au-layer was found to be unstable after prolonged incubation in crystal violet solution. The inherent deficiency in adhesiveness of Au to the glass limits its use as a reliable and cost-effective substrate. In an attempt to improve the SERS-substrate, bimetallic substrate was fabricated by depositing the Au-film, as a protective layer, on the Ag-substrate. In this case, the top layer of Au of the bimetallic substrate remained intact after chemical treatment. Furthermore, the bimetallic substrate was shown to give comparable level of enhancement as an Ag-substrate by choosing a proper thickness ratio of the bimetallic layers. The result suggests that the design of bimetallic substrate could be optimized to maximize the SERS enhancement while retaining a decent stability after laser illumination and chemical treatment. Our findings suggest that bimetallic substrates are potentially useful for a reliable SERS-based biosensing.

Paper Details

Date Published: 27 August 2009
PDF: 10 pages
Proc. SPIE 7397, Biosensing II, 739717 (27 August 2009); doi: 10.1117/12.827012
Show Author Affiliations
Chit Yaw Fu, Singapore Bioimaging Consortium (Singapore)
Zhen Yu Koh, National Univ. of Singapore (Singapore)
Kiang Wei Kho, National Cancer Ctr. of Singapore (Singapore)
Dinish U. S, Singapore Bioimaging Consortium (Singapore)
Thoniyot Praveen, Singapore Bioimaging Consortium (Singapore)
Malini Olivo, Singapore Bioimaging Consortium (Singapore)
National Cancer Ctr. Singapore (Singapore)
National Univ. of Singapore (Singapore)

Published in SPIE Proceedings Vol. 7397:
Biosensing II
Manijeh Razeghi; Hooman Mohseni, Editor(s)

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