RAMAN APPLICATIONS IN CANCER STUDIES - Raman Spectroscopy for Soft Matter Applications - page 262

calorimetry, and so on, spectroscopic methods provide useful and
detailed chemical structural information. Raman spectroscopy is one
of the spectroscopic methods that can be suitably applied to biological
soft materials [1]. From a viewpoint of in vivo capabilities, Raman
spectroscopy is superior to other spectroscopic methods, such as nuclear
magnetic resonance, infrared absorption, dielectric spectroscopy, and
UV-visible spectroscopy. In order to optimize the advantages of Raman
spectroscopy, it is essential to use an excitation wavelength as long as
possible (see more detailed discussion below). Fortunately, we are
equipped in our laboratory with a prototype near-infrared multichan-
nel detector that has the highest sensitivity so far in the deep near-
infrared region up to 1.4 m. In this chapter, we introduce our 1064- nm

excited near-infrared Raman system that uses this detector as a
state - of - the - art

μ

spectroscopic tool for investigating biological soft

materials.
Rapid progress in noninvasive clinical diagnoses of cancers has been
made with the recent development of medical imaging techniques such
as ultrasonography, computed tomography, nuclear medicine, positron
emission tomography, and magnetic resonance imaging (MRI). In spite
of this progress in noninvasive cancer diagnosis, there still remain a
number of occasions in which biopsy has to be chosen. Biopsy is an
invasive procedure that can cause serious damage in patients. Further-
more, considerable time and cost have to be spent in taking the biopsy
sample, and specialized knowledge of a pathologist is required in the
diagnosis. In order to overcome these diffi culties with biopsy, introduc-
tion of a more advanced noninvasive diagnosis method has been longed
for. Raman spectroscopy has already been shown to be ideally suited
for noninvasive diagnosis of cancers at the molecular level [2 - 25] .
As was discussed in Chapter 2, Raman spectroscopy is based on
Raman scattering, discovered by C.V. Raman in 1928 [26]. Thanks to the
technical developments of lasers, optical electronics, and computers, it
showed a tremendous development after the 1970s. Raman spectros-
copy was born and grew up in the 20th century. The major three advan-
tages of Raman spectroscopy are as follows: (1) The Raman spectrum,
referred to as “the molecular fi ngerprint, ” sensitively refl ects the
structure of molecules. It is straightforward to extract information on
structures, structural changes, and how they interact with their environ-
ments, once Raman spectra are obtained. (2) Since sample pretreatment
procedures are unnecessary, it is possible to examine an untreated
sample in vivo or in situ . In fact, Raman spectroscopy is applied to a
variety of materials, from molecular systems, such as solids, liquids, solu-
tions, and gases, to biological and medical systems, such as living cells and