Biomedical Engineering Reference
In-Depth Information
required to improve their characteristics towards better cell adhe-
sion, proliferation, viability, and enhanced ECM secretion functions.
This is usually done by functionalizing the matrices with bioactive
species or chemical compounds. In this aspect, emphasis is usually
on the surface engineering as this is the barrier that will be in con-
tact directly with the cells. As this area covers an important key fac-
tor in the success of utilizing a biomaterial, intensive research and
reviews on this subject matter have been undertaken. In general,
it is reported that such an approach consists of three steps, which
arethemodificationstepinvolvingdifferenttechniques,assessment
and characterization of the materials, and a biocompatibility test
through biologically related studies.
66
Modification for functional-
izing purposes can be carried out with different synthetic routes
such as grafting, adsorption, and blending, depending on the mater-
ial suitability. General principles and techniques used for the modi-
fication will not be further discussed in this section as that informa-
tion can be readily obtained from the literature.
56
,
66
,
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Such modifi-
cationisalsorequiredfortheORMs,dependingonthefinalintended
application, and the standard protocols from the literature can be
used.
Particularly in developing ORMs, there is an extra need for
functionalizing the matrix with the capability of decomposing the
free H
2
O
2
into oxygen and water besides the common proper-
ties required as tissue scaffolds. Various catalysts for decomposing
H
2
O
2
, chemical or biological, can be used as a coating layer on the
microsphere surface to serve this purpose. However, the mobility of
the catalyst needs to be confined, and it should not be released into
the surrounding, which may cause serious contamination. In this
case,abiologicalcatalyst,specificallycatalase, canbeemployedand
immobilizedonthebiomaterialsmatrix.Catalaseischosenduetoits
specific activity towards H
2
O
2
decomposition with a fast turnover,
ease to be obtained with considerably low cost, and most impor-
tantlythepossibilitytocarryoutimmobilizationcovalentlyorphys-
icallyinto a matrix.
Covalent immobilization is more preferable as the chances of
contaminating the biological surrounding will be lowered and the
immobilization protocols for catalase are well reported.
68
-
70
One
possible covalent method is via the use of glutaraldehyde as a
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