Biomedical Engineering Reference
In-Depth Information
Ó Faoláin et al. compared the effects of various physical and chemical treat-
ments [70] and concluded that tissue degradation as a result of freezing or
wax-embedding can lead to spectral differences. It may be challenging to
create protocols that can deal with multiple different sample treatments.
While sectioning is necessary for transmission or reflection-absorption
measurements, reflectance and ATR methods can potentially be used to
measure the spectra of fresh samples (possibly even in vivo with fibre optics),
but reflectance may be more prone to artefacts and instrumentation for ATR
studies may require customisation.
FTIR imaging has allowed analysis of the same specimen used for histo-
pathological evaluation, as described in Table 5.1. Breast cancer tissues were
analysed to demonstrate that chemical changes taking place in biological
tissue can be identified precisely and the results are reproducible.
The analysis of natural tissues and biomaterials by spectroscopic means
has had great impact on the development of specific structure-property
relationship in materials. For biomedical applications, the composition and
structure of these materials is of great importance since interactions with
biological environments has a significant impact in predicting long-term
behavior.
As described earlier, FTIR spectroscopy is a widely used tool for struc-
tural and compositional analysis of natural materials due to its relatively
simple, nondestructive capability and allows analysis of characteristic group
frequencies in a spectrum that provides qualitative estimates of chemical
composition in natural materials. Structural factors such as linear chains,
branching, or cross-linking can also be measured. In addition, the nature
and quantity of any imperfections can also be determined.
With new technological advances in the field of spectroscopy, applications
of FTIR spectroscopy have increased a great deal and numbers of new
clinical studies reported in the literature are increasing at a rapid pace due to
the advances in FTIR and perhaps more importantly due to the better under-
standing and interpretation of the spectral data. FTIR rapid scan imaging
is a prime example, where a cancer sample, as described earlier, can be
effectively imaged and the chemical distribution of various components
extracted from the image in a very short time span. It is well-established
fact now that cancer is a genetic disease resulting from various mutations
in specific genes. These mutations, which may either abrogate gene func-
tion or increase gene function, drive the cell toward the unregulated and
irreversible cellular proliferation that is the hallmark of cancer. Over the last
15 to 20 years, considerable progress has been made in defining and under-
standing these changes at the molecular level. There is a need to understand
the chemical structure of cancer tissue and compare it with healthy tissue
to monitor the chemical changes precisely and accurately. This will help to
understand the chemical pathways to cancer formation, as FTIR rapid scan
imaging has made it possible to obtain the visual image and relate it to the
chemical structure profile of the samples.
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