production of selected secondary metabolites in transformed ...

Table 1 Sum of the cac values for all samples
sample SD cac
- % x10 6 mol·l -1
D 44
D 134
D 183
D 360
D 1470
In Figure 4 there are typical
dependencies of the pyrene and perylene
in hydrophobized hyaluronan solution.
Pyrene ratio shows typical decreasing Stype
curve. Perylene, on the other hand,
shows two line system. For pyrene it was
used equations 1) and 2) to solve
parameter cac1 and cac2, respectively.
Perylene’s data, cacPe was solved by
combination of two linear equations as
point of intersection. Final values (in
g·l -1 ) are: cac1 = 0.179, cacPe = 0.178,
cac2 = 0.758. So it was established the
best value for the cac determination is
cac1 point, realized as the inflex point x0.
The cac values are showing two
trends. First, the cac values are
decreasing with increasing SD (except for
samples D 1470). Second, the cac values
are decreasing with increasing M. These trends are obvious in Figure 5 and summarized in
Table 1. The greatest decreasing of the cac values show D 44 samples. It is possible to relate
this behavior to the fact that D 44 samples have the shortest chains and new types of
interactions can be founding. On the other hand, heavy weighted chains show stable behavior
against the SD changes. These results can be explained if we accept that next addition of the
alkyls to the chain only fortify chain-chain interaction. And in fact, it does not lead to the
formation of new hydrophobic cores.
cac (10 -6 mol l -1 )
100.00
10.00
1.00
0.10
0.01
10
30
50
10
30
50
70
10
30
50
10
30
50
30
50
70
12.27
1.02
0.06
4.35
1.21
0.76
0.20
0.99
0.73
0.47
0.51
0.19
0.18
0.15
0.06
0.10
D 44 D 134
D 183 D 360
D 1,470
0 20 40 60 80
SD (%)
Figure 5 The dependences of the cac values on the SD. Except for D 1470 all samples
show the decreasing tendencies with increasing M and SD.
CONCLUSION
Fluorescence determination of cac for the novel hyaluronate derivatives was presented. It
was showed cac1 as the best point for determination of the critical aggregation concentration.
Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006
Sekce DSP 2006, strana 216