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High Sensitivity Surface Enhanced Raman Scattering Detection of Tryptophan Open Access


Other title
Surface enhanced Raman scattering (SERS)
Microfluidic chip
SERS substrate
Teflon AF capillary
Liquid core waveguide
Silver colloid
Raman scattering
Type of item
Degree grantor
University of Alberta
Author or creator
Kandakkathara, Archana A
Supervisor and department
Fedosejevs, Robert (Electrical and Computer Engineering)
Examining committee member and department
Tsui, Ying (Electrical and Computer Engineering)
Zemp, Roger (Electrical and Computer Engineering)
Brolo, Alexandre (Chemistry)
Jaeger, wolfgang (Chemistry)
Jacob, Zubin (Electrical and Computer Engineering)
Department of Electrical and Computer Engineering
Photonics and Plasmas
Date accepted
Graduation date
Doctor of Philosophy
Degree level
Raman spectroscopy has the capability of providing detailed information about molecular structure, but the extremely small cross section of Raman scattering prevents this technique from applications requiring high sensitivity. Surface enhanced Raman scattering (SERS) on the other hand provides strongly increased Raman signal from molecules attached to metallic nanostructures and thus a promising technique for high sensitivity analytical applications. However, there are issues which have to be addressed in order to make SERS a reliable technique such as the optimization of conditions for any given analyte, understanding the kinetic processes of binding of the target molecules to the nanostructures and understanding the evolution and coagulation of the nanostructures, in the case of colloidal solutions. In the present thesis the goal was to develop very sensitive SERS techniques for the measurement of biomolecules of interest for analysis of the contents of cells. The techniques explored could be eventually be applicable to microfluidic systems with the ultimate goal of analyzing the molecular constituents of single cells. A high sensitivity detection system based on SERS has been developed and spectrum from tryptophan (Trp) amino acid at very low concentration (10^−8 M) has been detected. The concentration at which good quality SERS spectra could be detected from Trp is 4 orders of magnitude smaller than that previously reported in literature. A study on background electrolytes in the solution which has a significant role in SERS experiment has also been carried out. Optimization of electrolytes leads to the high enhancement reported in this thesis. The SERS detection has also been performed in microfluidic and flow cell geometries which enable a combination of high sensitivity of the SERS with the low volume requirements of microfluidic devices. A Teflon AF capillary was used for performing liquid core waveguide (LCW) SERS measurements and with this geometry the enhancement obtained was increased by a factor of 10. The enhanced sensitivity and better understanding of the optimum conditions for SERS developed in the thesis are important since they now could allow the possibility of assays of the chemical constituents of single cells in future microfluidic systems.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
A. Kandakkathara, I. Utkin, and R. Fedosejevs. Physica Status Solidi (C), 6(S1):S27–S30, May 2009.A. Kandakkathara, I. Utkin, and R. Fedosejevs. Proceedings of SPIE, 7386:73860A –73860A–7, 2009.A. Kandakkathara, I. Utkin, and R.Fedosejevs. Applied spectroscopy, 65(5):507–513, 2011.

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