Biomedical Engineering Reference
In-Depth Information
(the reference, curve 0). The decline of dynamic viscosity (h) of the
reference (curve 0) corresponds to the value 4.77 mPa.s after a 5-h
treatment. By applying the experimental setting (a), the addition of
acetic acid triggered degradation of HA and the value of h declined
by 5.11 mPa.s (curve 1). By applying the experimental setting (b) the
decline of h was somewhat greater and was 5.53 mPa.s (curve 2).
H
H
O
O
O
O
HO-HC
HO-HC
+ e
-
+
+
Cu (II)
H
2
HO-H
2
C
HO-H
2
C
-
H
O
H
O
O
AscH
-
O
O
O
Cu (I)
H
H
O
O
O
O
HO-HC
HO-HC
+ H
+
- e
-
Cu (II)
H
2
O
2
HO-H
2
C
HO-H
2
C
O
O
O
O
DHA
O
O
H
Cu (I)
H
2
O
2
+ Cu(I)--- complex
→
·
OH+ HO
-
+ Cu(II) --- complex
Scheme 5.1
WBOS
Hyaluronan itself shows a slight degradation in acidic conditions at
pH below 1.6 and in a basic medium at pH above 12.6. However
the rheological behaviour is not influenced much by pH [28]. The
acidic character of our reaction mixture (pH about 4) can account
for a rapid HA degradation.
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