Biomedical Engineering Reference
In-Depth Information
GP-1/ISA gel, No additive
Tip branching
GP-1/ISA gel, with Tween 80
Enhanced tip branching
GP-1/PG gel, no additive
Tip branching
GP-1/PG gel, with span 20
Side branching
(a)
(b)
(c)
(d)
17:22:51:00
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19:50:35:09
1x Lens
06-08-07
100
μ
m
100
μ
m
2
30%
44.27
°
C
2 30%
Cool rate too fast
46.69
°
C
Cool rate too fast
Daughter
fibers
(e)
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Parent fibers
(g)
(h)
Daughter
fibers
100
μ
m
2
30%
46.76
°
C
Limit
HELD
9999
(Surfactant-enhanced tip branching)
(f)
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GP-1 molecule
(i)
Surfactant molecule
(Surfactant-enhanced side branching)
Hydrophobic tai
Hydrophilic head
100
μ
m
2
30%
39.86
°
C
Limit
HELD
9997
(Surfactant micelle templated
Fiber network formation)
Figure 2.8
Surfactant-enhanced tip branch-
ing (a,b) and side branching (c-e) of
GP-1 fibers formed in solvent isostearyl
alcohol (ISA) (a,b) and propanol glycol
(PG) (c-f ). (g,h,i) illustrate the surfactant
enhanced tip, side branching, and surfactant
micelle-templated fiber network formation,
respectively. (a)-(f) are reproduced with
permission from Refs. [4a, 6b].
where
B
is the kink kinetics coefficient,
f
(
f
≤
1) is factors describing ratio
between the average effective collision in the presence of substrates and that of
homogeneous nucleation (no substrate).
Integrating Equations 2.20 and 2.22 into Equation 2.21, we have
exp
kT
2
γ
cf
3
kT
)
5
/
6
f
”
f
1
/
2
2
/
3
C
2
β
st
(
μ/
16
π
f
ξ
∼
(2.23)
3
μ/
kT
where
C
2
=
C
1
/B
,
The branching mechanism described by Equation 2.23 has been verified by the
linear correlation between ln[
/kT
)
−
1
] and 1/(
/kT
)
2
obtained for several
ξ
(
μ
μ
gels [6c, 8, 12a].
In a recent work, the crystallographic mismatch-induced fiber branching of HSA
was examined on a molecular scale using synchrotron Fourier transform infrared
(FTIR) spectroscopy [19]. It was observed that the lengths of the HSA fibers were
influenced by crystallographicmismatches resulting from the incorporation of HSA
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