Chemistry Reference
In-Depth Information
TABLE 3.1
Surface and Aggregate Properties
G
(×10
−
6
mol/m
2
)
g
(mN/m)
c
M
(×10
−
3
)
a
m
(Å
2
)
r
H
(nm)
Phospholipid
3.15
(Foss et al. 2005b)
57
1.3
4.5
39
8 and 100
Crocin
3.7
(Nalum Naess et al. 2006)
52
0.82
1.4
115
150
Cardax
3.19
(Foss et al. 2005c)
60
0.45
0.7
240
1300
Lysine derivative
3.20
(Nalum Naess et al. 2007)
58.5
2.18
0.7
240
110
Phospholipid C2
3.32
(C. L. Øpstad, Trondheim,
unpublished)
47
1.66
2.4
71
290
Phospholipid C6
3.33
(C. L. Øpstad, Trondheim,
unpublished)
50
1.11
2.1
81
235
C30 acid salt
3.36
(Foss 2005)
48
1.1
2.5
66
0.9
mg Crocin/mL H
2
O
0.6
10
4
2
1
0.5
0.2
0.02
0.3
0.0
300
400
500
600
λ (nm)
FIGURE 3.4
UV-VIS spectra of crocin
3.7
monomers (low concentration of crocin in water, λ = 445 nm)
and crocin aggregates (high concentration of crocin
3.7
in water, λ = 410 nm). Monomer-aggregate equilib-
rium concentration
c
= 1 mg/mL, cf.
c
M
= 0.8 mg/mL from tensiometric determination. (Reprinted from Nalum
Naess, S. et al.,
Helv. Chim. Acta
, 89, 45, 2006. With permission.)
alternative way to determine
c
M
for hydrophilic carotenoids, provided the absorption maxima of
the monomer and aggregate are easily distinguishable. If this is the case the concentration where
aggregates and monomers are in equilibrium corresponds to
c
M
. The UV-VIS spectroscopically
determined
c
M
was consistent with the
c
M
from tensiometric measurements, Figure 3.4 (Nalum
Naess et al. 2006, 2007).
3.5 AGGREGATE STRUCTURE
“Aggregate” is a general term for molecular associations. In textbooks, aggregates are often repre-
sented as spherical structures, with good reason—since a ball or sphere is a geometrically, gravi-
tationally, and energetically favored structure. Simple aggregates of spherical shape are micelles.
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