Recently, there has been significant
interest in using polarization gating to selectively probe
superficial tissue to facilitate the diagnosis of epithelial
neoplasia. Thus, understanding the propagation of polarized light
in tissue in general and the mechanisms of polarization gating in
particular are crucial for a number of biomedical optics
applications. However, these investigations have been
impeded in part by the lack of realistic tissue models that can
replicate both the morphological complexity and the optical
properties of biological tissue.
We
developed a novel bioengineered connective tissue model to study light
transport in biological tissue. This tissue model was fabricated
by the combination of scaffolding and crosslinking techniques.
It demonstrated great similarity to real connective tissue
in its optical properties as well as microarchitecture. Moreover, the physical and optical
properties of the model can be easily and reproducibly controlled.
We are utilizing this model to study the effect
of epithelium and the underlying connective tissue on the depth
selectivity of polarization gating.
Figure 1.
The optical properties of the tissue
model can be controlled by varying synthesis conditions.
(a) The dependence of the
scattering coefficient
ms (l =
632.8 nm) on the concentration of the glutaldehyde solution. (b)
The dependence of
the anisotropy factor g (l = 632.8 nm)
on
the freeze-drying pressure. (c) The
dependence of the absorption coefficient ma (l = 543.5 nm)
on the concentration of the hemoglobin solution.
Figure 2. Scanning Electron
Microscope (SEM) images of
(a) the rat colonic connective (b) bioengineered connective
tissue model. The scale bar
is 1 mm
.
Publication
Y. Liu, Y. L. Kim, V. Backman,
"Development of a Bioengineered Tissue Model and Its Application in the
Investigation of the Depth Selectivity of Polarization
Gating", Applied Optics, in press (2005).
