Biomedical Engineering Reference
In-Depth Information
Simplifying,
(
)
(
)
1/2
1/2
dd
pp
W
=
2
γγ
+
2
γγ
(6.6)
A
SVLV
SVLV
d
LV
p
LV
for a few of the compounds are given in Table 6.2. There are two
unknowns in (6.6),
γ
and
γ
d
LV
p
LV
γ
and
γ
, the components of the solid surface energy. Rear-
ranging (6.6)
1/2
W
⎛
γ
p
⎞
(
)
(
)
1/2
1/2
d
p
A
=
γ
+
γ
LV
⎜
⎟
(6.7)
(
)
SV
SV
1/2
d
⎝
γ
⎠
2
γ
d
LV
LV
Contact angle data from at least two liquids of different polarity are measured
W
γ
12
⎛
γ
γ
p
LV
d
LV
⎞
A
from which
W
A
is calculated. Then,
is plotted against
and from
(
)
12
⎜
⎟
2
d
LV
⎝
⎠
d
LV
p
LV
the slope and intercept values of the linear line
γ
and
γ
can be calculated us-
ing. Then the net surface tension
γ
SV
is calculated using the relation
(
) (
)
γ
=
γ
d
+
γ
p
(6.8)
SV
SV
SV
EXAMPLE 6.2
d
LV
,
γ
p
LV
, and the
γ
SV
.
Using the
W
A
obtained in the Example 6.1, calculate the
γ
d
LV
(dyne/cm)
(dyne/cm)
γ
SV
p
LV
γ
γ
(dyne/cm)
PUDPA1 19.3 2.3 21.6
PUDPA2 9.1 14.2 23.3
Solution: Using the
W
A
values, calculate the
x
and
y
coordinates. From the slope and
intercept, dispersion and polar components can be obtained.
Polymer
To understand whether the plasma proteins attach and which one has a prefer-
ence over the other, interaction of serum albumin and serum fibrinogen with the
material surfaces are evaluated. The preferential binding of fibrinogen over albu-
min indicates the possibility of thrombus formation as albumin shows thrombore-
sistant properties. The interfacial tension,
, between the surface of the biomaterial
and the absorbed protein is mainly determined by
Γ
2
2
()
()
()
()
⎡
1/2
1/2
⎤
⎡
1/2
1/2
⎤
(6.9)
d
d
p
p
Γ=
γ
−
γ
+
γ
−
γ
⎢
⎥
⎢
⎥
⎣
⎦
⎣
⎦
ij
S
S
S
S
i
j
i
j
