Abstract:
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The main goal of this experimental project is to study the properties of three important
biomaterials used for bone scaffold production in tissue engineering: polymer/glass composites,
glass ceramics and calcium phosphate cements. The main topic of investigation
is the permeability which depicts to what extent fluids are capable to pass through the
material. This property is of major importance in tissue engineering applications, more
specifically in cell seeding experiments, since it reflects the interconnectivity of the pores
and determines the values of parameters, such as seeding velocity, pressure, etc., in order
for cells to penetrate and attach to the scaffolds. Furthermore, porosity and compression
characteristics are examined.
First, a general introduction sets the context for the project. This introduction describes
the state of the art in tissue engineering and some general concepts, such as
applications of scaffolds, bioreactors, etc. Secondly, experimental set-up and methods
are discussed which were necessary for measurement and analyses of the three types of
biomaterials. Cements and ceramics are studied less extensively than composites because
fewer samples were available for testing. Finally, the three biomaterials are compared and
conclusions are drawn.
The permeability results for composite scaffolds show a remarkable time dependency,
i.e. permeability seems to decrease with perfusion time. In order to explain this phenomenon
mechanical tests are done, porosity is measured and SEM-images are taken.
These results exclude several possible causes, but they are not able to reveal the actual
source of the occurring phenomenon. Statistical analysis of the permeability results proves
the appearance of large variability between scaffolds made of the same material. Samples
with similar porosity may display significantly different permeability behaviour since
permeability is susceptible to various parameters. For instance, pore size and especially
interconnectivity have a major influence on a material’s permeability. Glass cements show
a similar decreasing permeability whereas cements show a different time course. When
comparing the three materials on the basis of the examined properties, it is to be concluded
that composite scaffolds offer the best prospects for use in cell seeding applications. |