Biomedical Engineering Reference
In-Depth Information
categories: (i) morphology like porosity, pore size, and surface area,
(ii)mechanicalpropertieslikecompressiveandtensilestrength,(iii)
bulk properties like degradation and its relevant mechanical prop-
erties,and(iv)surfacepropertieslikesurfaceenergy,chemistry,and
charge.
Porosityisdefinedasthefractionofthetotalvolumeoccupiedby
voids and appears in percentage. Most widely used methods for the
measuring of porosity are mercury porosimetry, scanning electron
microscopy, and confocallaser microscopy.
Mechanical properties are extremely important when designing
tissue-engineered products. To determine the mechanical proper-
ties of a porous structure, conventional testing instruments can be
used. Mechanical tests can be divided into (i) creep tests, (ii) stress-
relaxationtests,(iii)stress-straintests,and(iv)dynamicmechanical
tests.Thesetestmethodsaresimilartothoseofconventionalbioma-
terials everywhere.
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The rate of degradation of manufactured scaffolds is one of the
most important factors for designing tissue-engineered products.
Ideally, the scaffold constructs provide mechanical and biochem-
ical supports until entire tissue regeneration occurs without any
changes, and then completely biodegrade at a rate consistent with
tissue generation. Immersion studies are commonly conducted to
track the degradation of a biodegradable matrix. So, the changes
of weight loss and molecular weight can be evaluated by chemical
balance, scanning electron microscopy, and gel permeation chro-
matography. From these results, we can expect the mechanism of
biodegradation.
It is generally recognized that the adhesion and prolifera-
tion of different types of cells on polymeric materials depend
largely on surface characteristics such as wettability (hydrophilic-
ity/hydrophobicityofsurfacefreeenergy),chemistry,charge,rough-
ness, and rigidity. Especially, 3D applications for tissue engineering
are more important to cell migration, proliferation, DNA/RNA syn-
thesis, and phenotype presentation on the scaffold materials. Sur-
face chemistry and charge can be analyzed by electron-scanning
chemical analysis and streaming potential, respectively. Also, wetta-
bility of the scaffold surface can be measured by contact angle with
static and dynamicmethods.
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