Biomedical Engineering Reference
In-Depth Information
Fig. 2.13
The effect of AFP
III on the ice nucleation
kinetics and the
corresponding shift in the
ln(
V
)
1/(
T
T
2
) plot.
Reprinted with permission
from ref. [
54
]. Copyright
(2003) the American Society
for Biochemistry and
Molecular Biology
Tabl e 2. 3
Effect of AFP III on the interfacial effect parameter and kink kinetic energy barrier
for the nucleation of ice
Curve
G
=G
DIwater
a
.G
kink
=kT /
add
f
(
m
)
m
DI water
b
1.21 10
8
0.2
1
0.43
-
0.39 10
8
AFP III(0.5 mg/mL)
0.35
1.75
0.20
" 13.7
0.32 10
8
AFPIII (2.5 mg/mL)
0.45
2.25
0.07
" 13.9
a
G
=G
DIwater
D f.m/
AFPIII
=f . m /
DIwater
b
DI water: deionized water
which decreases from 0.43 to 0.2 and 0.07 and the enhancement of the nucleation
barrier by a factor 1.75 and 2.25, for a 0.05 wt% and 0.25 wt% solution, respectively.
The results given in Fig.
2.13
and Table
2.3
show that AFP III will also adsorb
onto the growing ice nuclei. This can be seen from the increase in the desolvation
kink kinetics barrier G
kink
(13.7
kT
for 0.05 wt% solution, 13.9
kT
for 0.25 wt%
solution, cf. Table
2.3
).
It is worth noting that the presence of the AFP III molecules on the surface of
the embryos causes the interfacial free energy
cf
between the crystalline phase
c and mother phase f to decrease. Based on (
2.27
), this change will lower and
induce nucleation promotion. However, the aforementioned analysis shows that this
promotion effect is not dominant compared to the other two inhibition effects of
AFP III.
2.3
Ice Crystal Growth Inhibition by Antifreeze Proteins
2.3.1
Ice Crystal Growth Inhibition
As ice crystallization includes both nucleation and growth, once the inhibition of ice
nucleation fails, AFPs should proceed to inhibit the growth of ice.
