Chapter 1
New Tools for Life Science Research Based on Fiber-Optic-Linked Raman and Resonance Raman Spectroscopy 1
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M. W. Blades , H. G. Schulze , S. O. Konorov , C. J. Addison , A. I. Jirasek , and R. F. B. Turner Downloaded by 5.101.222.229 on May 19, 2016 | http://pubs.acs.org Publication Date: August 2, 2007 | doi: 10.1021/bk-2007-0963.ch001
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Department of Chemistry, The University of British Columbia, 6174 University Boulevard, Vancouver, British Columbia V6T 1Z3, Canada Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 3P6, Canada 2
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Fiber-optic probes can exploit a favorable excitation radiation distribution within the sample that allows the use of higher laser power levels which, in turn, can yield a higher signal-to— noise ratio (SNR) for a given experiment without increasing the risk of analyte photo-damage. We have developed specialized fiber-optic probes for ultraviolet resonance Raman spectroscopy (UVRRS) that offer several advantages over conventional excitation/collection methods used for U V R R S . These probes are ideally suited for U V R R S studies involving biopolymers and small bio-molecules, in both native (e.g. physiological) and non-native (e.g. anoxic) solution environments. We have also developed novel probes based on hollow-core photonic band-gap fibers that virtually eliminate the generation of silica Raman scattering within the excitation fiber which often limits the utility of fiber-optic Raman probes in turbid media or near surfaces. These probes may offer advantages for some biomedical applications.
© 2007 American Chemical Society
Kneipp et al.; New Approaches in Biomedical Spectroscopy ACS Symposium Series; American Chemical Society: Washington, DC, 2007.
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Downloaded by 5.101.222.229 on May 19, 2016 | http://pubs.acs.org Publication Date: August 2, 2007 | doi: 10.1021/bk-2007-0963.ch001
2 Many spectroscopic methods based on the Raman effect, the inelastic scattering of light by molecules, have been developed and employed in various biophysical and bioanalytical applications (1-4). The value inherent in all of these methods lies in the rich information content of Raman spectra due to the dependences of molecular vibrational modes on the chemical and physical microenvironment of the analytes. However, exploiting this information content can be quite challenging due to fundamental limitations in the sensitivity of the technique and/or practical limitations in the available experimental systems. Much effort has therefore focused on the development of instrumental configurations that endeavor to optimize the utility of the technique for a given application or class of applications. Fiber-optic probes offer many obvious advantages in terms of experimental flexibility and remote measurement capability, and numerous probe designs have been reported (5,6). In biomedical spectroscopy applications, fiber-optic probes also offer some valuable performance advantages. For example, since the excitation light is not tightly focused, as it normally is in conventional Raman spectroscopy, substantially higher excitation power fluxes can be used, which results in higher levels of Raman signal generated within the illuminated volume. This power-distribution advantage (7) is particularly useful for ultraviolet resonance Raman spectroscopy (UVRRS) of biomolecules where sample damage thresholds can be quite low (
