Biomedical Engineering Reference
In-Depth Information
adhesion and activation. Because phosphorylcholine is a lipid head found
naturally in cell membranes, MPC is considered to reduce interactions
with biocomponents such as proteins and cells. The photoreactive polymer
is synthesized by coupling 4-azidoaniline with a copolymer containing
MPC and methacrylic acid as shown in Figure 11.9 [40, 41]. The synthe-
sized polymer was used for coating onto surfaces such as polyethylene
and polypropylene. Micropatterning was carried out using photomask-
ing, and the adhesion of RAW264 cells onto the resultant micropatterned
photoreactive phospholipid polymer was investigated. As interactions
between the surface and the cells were observed, there was a signifi cant
difference between nonimmobilized and immobilized regions. The immo-
bilized region did not show any adherence of cells and form aggregates,
but the nonimmobilized region did. In addition, human blood platelets
showed reduced adhesion and reduced protein adsorption to the immobi-
lized regions. Hence, this surface modifi cation with a photoreactive phos-
pholipid polymer can be used for biomedical applications that require
bio-nonfouling properties.
11.3.1.2 Sulfobetaine
A sulfobetaine group containing a photoreactive polymer was synthe-
sized by copolymerization using 4-azidophenyl methacrylamide and
2-(
N
-3-sulfopropyl-
N
,
N
-dimethyl ammonium)ethyl methacrylate with
2,2'-azobis(isobutyronitrile) (AIBN) as an initiator as shown in Figure 11.10a
[42]. The synthesized polymer was coated and photoimmobilized on poly-
meric surfaces such as polystyrene and polyester by UV irradiation. The
immobilization of sulfobetaine onto the coated surface was characterized
by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) by deter-
mining the sulfur content. The surfaces turned hydrophilic, as determined
NH
2
CH
3
CH
3
C
C
O(CH
2
)
2
OPO(CH
2
)
2
N
+
(CH
3
)
3
+
CH
2
(CH
2
C)
C
OH
10
90
O
-
O
O
N
3
O
EDC
CH
3
C
C
O(CH
2
)
2
OPO(CH
2
)
2
N
+
(CH
3
)
3
CH
3
C)
C
OH
CH
3
C)
C
NH
CH
2
(CH
2
(CH
2
4
6
90
O
-
O
O
N
3
Figure 11.9
Synthesis of a photoreactive phosphobetaine polymer by coupling
azidoaniline and a copolymer.
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